[Verizon Samsung Galaxy S III] Neverendingxsin:
This is going to be a long post, but please bare with me. The reason for this post is too hopefully reduce the number of "Help me choose a rom" threads, as they seem to get posted quite frequently, and ask basically the same questions. So in this thread ill be going through some of the basics, as well as some highlights of each type of rom :)

Introduction

I wrote this thread in an effort to make things easier for "noobies" or "new users" whichever you'd like to call them, so that they can have a better understanding of what the various types of Rom's are out for the Galaxy SIII or may be out in the future. Here's a very common question, what is a rom? A rom on our android phones is like the operating system on your computer, it controls the user interface, what you see and what you can do. Thankfully we have developers who have taken the stock rom's and changed them up and made them 'better' so that we the users can unlock the full potential of our phones. In this thread i will do my best to give you a brief outline of what you can expect with the different types of roms, and what bugs you may encounter. What i will not do is make any claims as to what the 'best' rom is, or tell you what you should be running. I am simply going to give you the information that you need to better help understand what can be included with each rom type :)

***Disclaimer: Anything you do after reading this thread is on you, what you decide to flash or not to flash is on you. I am not to be held responsible for anything that you do to your phone. This is simply information to help guide you and teach you a few things about roms.***

What you won't find in this guide, but should familiarize yourself with:

These guides don't have to be read, but i highly recommend you at least glance over them to familiarize yourself with a few things, before flashing your first rom. They all contain important information that you should know :)

*Any instructions on rooting your phone or how to install a rom, those can be found here

*Any rom download list, that can be found here

*A way to get Google wallet to successfully work on your Verizon SIII, that can be found here

Important ------>*A guide to backup your IMEI, that is here<------ Important

Important ------>*An IMEI repair guide/tool, that can be found here<------ Important

*A way to unbrick your softbricked phone, that's can be found here

CHAPTER 1: Touchwiz Roms

***Based on samsung's touchwiz.

Section 1: Stock Rooted Roms

These roms are exactly how its said stock and rooted they are the OTA's that verizon puts out, the only difference is that they've been pre rooted for the rooted users who want to be rooted but just want that basic stock experience. They may come in two flavors: Odex and Deodex, the difference between the two is the way that applications (apk files) are packaged. Odex is the stock way, and Deodex is repackaged, if you're looking to make minor modifications or do a little themeing then you want Deodex because 99% of theme's are built for Deodexed ROMS. There isn't much to be said for stock rooted roms, you're going to get that stock experience that comes with the phone but with root capabilities (titanium backup, wifi tether, overclocking, etc)

-Is this for me? If you want that exact samsung touchwiz stock feel with nothing added in then yes this is for you.

Section 1A: Debloated Stock Rooted Roms

These roms are going to be "debloated" meaning most if not all the fat is taken out of them. In the SIII's case you're going to lose most of the samsung apps and verizon apps. With this you may also lose some of those touchwiz features (smart alert, direct call, etc) or verizon features (NFL mobile, my verizon, etc). The benefit? You're still going to be mostly stock, and you may notice a speed increase due to there being less fat in the rom. There are various levels of debloating as well, some are more extreme and have had everything removed except for the essentials, and some will only remove a few things. Its best to read the original post with each rom to have an idea of what has been removed.

-Is this for me? If you want the barebones experience without using AOSP the yes this is for you.

Section 2: Modified "Stock" Roms

These roms, are going to be the touchwiz rom's made for verizon phones, the base (what the rom is built on) will either come from OTA updates or from leaks. These roms are modified in someway, some more than others. The modifications can include a wide variety of things from the basic speed tweaks, enhancements, and themes to including custom kernels, removing the wifi notifications, extra toggles in the notification bar, 4 in 1 reboot menu, and many other things. They are in a sense stock, but at the same time not. Think of it as a developer taking something 'good' and making it 'great' they've added in the stuff that should have already been there from the start. They will generally be deodexed already, may or may not have been debloated to a point, and generally will have a lot of 'under the hood' enhancements.

-Is this for me? For most people this is for you. You'll have a lot of the touchwiz features that you've come to love such as the camera, smart alert, direct call, and other features, while also getting a much faster and generally better experience. You'll be able to flash themes easily (make sure to double check that the theme is compatible with your rom) root app's will work and you'll be happy.

Section 3: Leaked Roms

These roms, are built off of leaked builds/bases. They may be ICS, Jellybean, etc. These rom's generally may have bugs to begin with depending on the leak itself. Some leaks are a little more stable than others, generally the only time leaked builds have major bugs is when its a leak of the next android version (a leaked JB Touchwiz build for verizon) otherwise they'll generally be almost bug free. There isn't much to say about any leaks of the current version (SIII shipped with ICS Touchwiz) because those will generally just get merged into the custom builds and such. Leaks for future versions generally have bugs, some big, some small, but usually get worked out quickly depending on the bug.

Is this for me? If you're looking to get that future android feel before its official then yes its for you. But you have to be willing to accept that everything may or may not work, and may or may not get fixed before an official release happens. You'll have the latest and greatest though and be able to brag to you're friends about having it before they do.

Section 4: Ported Roms

These roms are ports, meaning they could come from a different carrier (Example: AT&T JB touchwiz on verizon), different manufacturer (Example: Sense 4.0 on SIII), etc. These rom's will almost certainly have bugs to begin with. They are in a way like leaked roms because they aren't "official" for the SIII, but also vastly different because they may not even be mean't for the SIII. These rom's generally require a lot of work to even get booted up because its based off something that's not even mean't for the verizon SIII and a lot of work goes into them. Bugs could range from little things like screen flickering to GPS being completely borked, to your phone not even booting up. After they've had some work hammered into them and testing done, they can be really functional as a daily driver.

Is this for me? If you're looking to have something different or the latest and greatest then yes its for you. But like i said with leaked rom's you have to be willing to accept that you may encounter a vast variety of bugs that may or may not get fixed quickly or at all depending on the bug.

CHAPTER 2: AOSP (Android Open Source Project) Roms

What you won't find in AOSP: Any touchwiz features, yes this includes the camera as well. This is because touchwiz features and apps require the touchwiz framework which is not in AOSP and probably never will be. You also will find that verizon apps tend to be hit or miss as well, most of the time they won't work either, yes this includes NFL mobile and My Verizon.

Known issues when going from ICS touchwiz to AOSP JB:

*GPS may not work correctly, the fix? Before flashing to AOSP JB make sure you have a full gps lock (i personally download gps status from the market and wait until almost all satellites are locked) then from in the app boot into recovery and do your usual wiping/flashing.

*NFC may not work correctly, the fix? Ensure NFC is turned on before flashing to AOSP JB (i personally don't use NFC so i can't comment on whether that works or not, but i've heard it does)

***Based on pure android, you won't have any kind of carrier/manufacturer features added in. If you've ever had a Nexus device then you'll know what this is.

***Themeing is also super simple, with AOSP you get the Theme chooser, which makes changing themes as simple as a few clicks, just download a theme chooser theme off the market and then go into theme chooser and apply it. It really is that simple, if you want to change back just apply the "system" theme, and bam you're back to normal :)

Section 1: CyanogenMod (CM)

The one's who started it out, they've been around for what feels like forever. This rom will be built straight from the latest source, and it'll be fast from the get go. You'll immediately notice that you've got a lot more RAM free off the bat and this is because there is absolutely no bloat in it at all. You'll have the pure google android experience, it'll be a love or hate thing. For CyanogenMod they generally have nightly builds for those who love to flash, and it'll have added in whatever they added/fixed for that day. These builds may be stable or may not be stable, today's nightly might suck while yesterday's was great. For these if you know what features the latest android version has most likely they'll be in CM, so if you stay up to date then you'll be good to go. Some features are added in though such as notification widgets/toggles, speed tweaks, various other shortcuts. They will generally keep it mostly stock android but also give you some treats that make it better. Bugs are hit or miss, especially for the SIII because pure AOSP android was not built for it originally so some things may be a little iffy (GPS, data, nfc, mms, call volume, etc) it doesn't mean they are all broken, but it's possible they are hit or miss at times, and you're miles may vary. For one person GPS might be fine and the other it could be broken.

Is this for me? If you're looking for that pure android experience without any manufacturer crap in it then yes its for you. Just know that you may encounter bugs that don't get worked out right away, some of them take time.

Section 1A: Unofficial CM Builds

These builds are based off of CM but they are unofficial because a developer wants to make nightly changes, and add in there own modifications, themes, fixes, enhancements, etc. They come with the same risk as official CM builds, but any bugs found in them should not be reported to the official CM bug tracker because then these are unofficial builds. There isn't anything wrong with them being unofficial, its just a developer wanting to add there own twist to the CM builds.

Is this for me? If you're looking for that pure android experience without any manufacturer crap in it then yes its for you. Just know that you may encounter bugs that don't get worked out right away, some of them take time. Please read the OP's thread to understand what changes they have added in.

Section 2: Android Open Kang Project (AOKP)

Almost just like CM but with a little more added in. Its based off the android source code and again won't have any manufacturer crap added in. With AOKP you'll get added in modifications that may not be found in CM, as well as other kinds of toggles, status bar mods, notification mods, etc. I can't say everything because its still based of android source and comes with the same risk as CM which is certain bugs or things not working (GPS, data, nfc, mms, call volume, etc) They know there stuff though and have "Builds" released from anywhere from day to day or weeks apart these builds are more major releases with various fixes, modifications, etc.

Is this for me? If you're looking for that pure android experience without any manufacturer crap in it, and more modifications than CM then yes its for you. Just know that you may encounter bugs that don't get worked out right away, some of them take time.

Section 2A: Unofficial AOKP Builds

These builds are based of off AOKP but they are unofficial because a developer wants to make there own changes, and add in there own modifications, themes, fixes, enhancements, etc. They come with the same risk as official AOKP builds, but any bugs found in them should not be reported to the official AOKP bug tracker because then these are unofficial builds. There isn't anything wrong with them being unofficial, its just a developer wanting to add there own twist to the AOKP builds.

Is this for me? If you're looking for that pure android experience without any manufacturer crap in it, and more modifications than CM then yes its for you. Just know that you may encounter bugs that don't get worked out right away, some of them take time. Make sure to read the OP to understand what has been changed in the build though.

Section 3: Paranoid Android

This rom is a phone/tablet hybrid rom. Its based off of pure android source just like CM, but has made vast changes to it. You'll be able to modify how each specific app shows up on the screen (want tablet mode only for youtube then you got it, want facebook to look bigger or smaller then you got it) and you'll get a wide variety of modifications as well. If you've ever watched a video of a tablet then you'll have an idea of what can happen. It truly is a phone and tablet hybrid, bringing the best of both worlds to your phone. It'll feel like pure android source and will have those features that come with that android version just with the tabletness added in. It comes with same possibility of bugs as other AOSP roms (GPS, data, nfc, mms, call volume, etc) these bugs are not guaranteed and may or may not occur. User A might have data issues but user B may not, your miles may vary with AOSP. Its a bit harder to explain everything for this rom, but i'm doing my best.

Is this for me? If your looking for pure android goodness but with a major overhaul of added in phone/tablet mode hybrid then yes its for you. Just be willing to accept that you may encounter bugs along the way.

Section 4: Other AOSP Roms

The reason i have this section is because its impossible to describe every kind of AOSP roms, especially when more can be added and such. But other AOSP rom's will come with the same pure android source as well, and will have those features. A lot of them merge in code from other various developers (with permission of course) but also add in there own toolkits, setting menus, etc. They are all great roms, but its hard to give every single one a section because its there all based off the same source and have some of the same kind of modifications added in. They all come with the same risk as other AOSP roms in terms of bugs (GPS, data, nfc, mms, call volume, etc) For these rom's you'll have to pick and choose, if you love a certain developer that makes AOSP roms, or have used a developers AOSP rom on a different phone then you'll know what to expect from that rom/developer. Again there is nothing wrong with these rom's its just hard to give all them all there own section when most of the information is going to be the same and repetitive.

Is this for me? If you're looking for that pure android experience without any manufacturer crap in it then yes its for you. If you follow a specific developer then yes its for you. Its going to have more modifications then regular CM or AOSP roms. You really have to test them out for yourself, just read the thread and see what they've changed/modified/added in. Just know that you may encounter bugs that don't get worked out right away, some of them take time.

Section 5: MIUI Rom

Miui is AOSP based but it won't look like it is. This is because with MIUI you get an entire different user interface experience. It's got its own custom toggles in the notification pulldown, its own theme engine (theme's have to be designed specifically for miui), its own camera app, and many other apps that are designed specifically for it. The main miui team puts out a rom in chinese once a week every friday, and it then gets ported to various devices including the SIII. The downside to miui is some things take a lot longer to get worked out in terms of bugs, this is because its ported to our phone but also because its a completely different interface with many applications that have to be worked on before they'll work flawlessly. Its got the same possibility of bugs as other AOSP roms. I've personally used it before on another device and ill tell you its definitely one of a kind, and fun to play with.

Is this for me? If you're looking for something completely and totally different then yes this is for you. Just know that because the larger builds are released once a week it may take time for some bugs to get worked out, but again you'll have something that's completely different from any of your friends as long as you can accept a few bugs here and there.

Section 6: Various Issues and Solutions

NFC Issues: Grayed out, won't turn on, etc. This is NOT a problem with rom itself, to solve this issue you will need to go back to a touchwiz rom and turn NFC on. Then boot into recovery and flash your respective rom choice If that still does not work flash this zip here in recovery after flashing your respective rom.

GPS Issues: Again not Rom related entirely, its more or less AOSP related. This problem again can be avoided by ensuring a full gps lock and leaving gps turned on prior to flashing. If you still have issues after that download GPS status from the market and use that to help with the gps lock. You can also flash this zip file here to help solve the issue

CHAPTER 3: Kernels/Battery life/Radios/Jelly Bean 4.2 Storage System

Section 1: Kernels

Okay kernels are one of the biggest advantages to rooting. They can be used to increase performance vastly, increase your battery life, make your phone faster, increase ram, etc. You can modify the clock speeds using apps to overclock or underclock the cpu, you can increase or decrease the voltage, etc. They are also what makes your phone boot up (flash a kernel mean't for touchwiz on AOSP and its not going to boot up) Kernels are built on two main bases for the SIII: Android Version (ICS, JB, etc) and Touchwiz/AOSP. This means that these kernels are used for specific rom bases and android versions. You have to make sure you read what the specific kernel is built for so you don't flash the wrong one and mess up your phone. Kernels are always your miles may vary, a kernel that works great for me and doubles my battery life, might make yours worse. You really can't guarantee any of that until you flash it on and modify the settings to your liking. Always make a backup before flashing a kernel so just incase your phone doesn't bootup you can easily restore the backup.

Section 2: Battery Life

This is another question i see asked all the time "What's the battery life like?" Battery life is based on a few things:

1. ROM Choice - Some roms might have better battery life than others. Your miles again will vary. You'll never get the same experience as another user.

2. Kernel choice and settings - some kernels work better than others in terms of battery life, what works for you may not work for me. But you can modify your cpu speed settings to help with this. Settings screen off profiles can help as well. I personally decrease the cpu to 384mhz while the screen is off, and it helps me, will it help you? I have no idea.

3. Personal Use - Self explanatory, if you're constantly using your phone, browsing the web, sending emails, playing music, gps, this and that then the battery might drain faster than somebody who doesn't use there phone as much. If you manage to get 3-4+ hours of screen on time then your battery life is fine. How quickly you reach that is based on your use. This also includes whether your still on the stock battery or not, if you've got an extended battery in your phone then your battery life may very well be a lot longer than somebody with the stock battery. You have full control over your personal use.

4. Coverage and Signal - If you're constantly in areas with terrible signal then your battery life will suffer. My suggestion? If you're near wifi turn it on, that way your signal won't matter as much because all your syncing and such will be done through wifi. There isn't much a rom or kernel developer can do about this, its just based on where you live.

5. Wakelocks and syncing - Make sure to download betterbatterystats, why? Because if your battery life sucks then your phone may not be going into deep sleep and this app can help tell you why. Wakelocks are anytime that your phone is awaken from deep sleep, the more wakelocks you have the less deep sleep you get which equals less battery life. Some of these wakelocks can be controlled because many are caused by syncing. If you have apps syncing every 10 minutes, don't expect super great battery life because your phone is constantly being awaken. Control your syncing, if you don't check twitter every 10 minutes then don't have it sync every 10 minutes. A lot of those apps will automatically sync upon being started.

6. Perception - I put this here because its true. Everybody expects something different with there battery life, so they perceive it that way. Some users want over 24 hours whereas some don't. For me personally i consider great battery life to be being able to leave for work at 6:45am, then go to class, then go to the gym, then do whatever else and come home. If i can make it from 6:45am to 8 or 9pm without being forced to charge then i consider that great battery life. Why do you say its great when its only 14 hours without charging? Because i charge my phone every night before going to bed, it may not even be less than 50% less but i still charge it so that's good enough for me since i made it through my day. Everybody has different expectations so don't always assume battery life sucks when somebody says it does because its based on there own perception of what's "great" and what's "bad"

Battery life is and always will be your miles may vary because there are just too many factors to consider. Some people who say "The battery life on this rom sucks" just have a runaway app killing there battery life and don't even realize it. The only true way to gauge battery is based on what you consider to be great battery life.

Section 3: Radios

Another question asked "What's the best radio?" Radios are always your miles may vary, its all based on your signal/coverage area. But there's also a big placebo effect that comes with radios, the second you flash a new radio, you expect the signal to be better so you see it that way. It might actually be better or it could be worse or exactly the same. Some users will get increased speed on one radio and somebody else might get decreased speed, but you can't base your radio stats right after flashing it because you need to test it in real world scenarios, not just sitting around looking at the dbm. I didn't originally plan on having this section but its necessary because in the future you may or may not need a specific radio for a specific rom to work. As of right now (10/22/2012) the radio you choose to use will work on any rom (make sure its a verizon radio) in the future though you may have to use specific radios for specific roms depending on the versions of android that come out, and when that happens you'll have to make sure you're using the right radio otherwise you may not get any kind of signal at all. Remember that radios are mostly user experience based, and what works for you might not work as well for somebody else.

Section 4: Jelly Bean 4.2 Storage System

Alright i'm going to do my best to explain this in the simplest way possible. With the introduction of 4.2 Jelly Bean, the storage/file system changed as well. What i mean by this is at least on AOSP roms when you flash a 4.2 Rom you'll get a "0" (zero) folder with everything from your internal SD card in it. The reason for this is because with the multi user support its the new way Android sorts stuff. Now many of you are probably wondering "Ummm... this is confusing" or "is this bad?" it is confusing at first but honestly its not that bad. The /storage/sdcard0 now points to /storage/emulater/legacy folder which is then emulated by the 0 folder. Easy version: Even if you put stuff in /storage/sdcard0 it'll automatically show up in those other folders anyways. It may look like you've got stuff duplicated, but its really not. Whatever file is on the sdcard0 (Internal card) is only there once.

The good news, if you update your recoveries to the latest versions, then you won't have to worry about any 0 folder nonsense anyways. You'll still have a legacy folder, but that's not a big deal. Just don't mess with it and your phone will be fine.

***If anybody has a better explanation for that, PLEASE let me know and i'll update/add it in :)***

I really hope that this thread can help reduce the number of questions asked about which rom to use and such. I put a lot of time into typing all of this out to help you guys, so hopefully it'll do just that and help :)

***MODS: feel free to move this if its in the wrong place or something***