[Android Head-Units] nixfu:
>community-supported ROMs

Yes, most of us are using the custom ROMs made by Malaysk.

>2GB RAM is highly desired.

They are all 1GB devices and use nearly the same integrated CPU/RAM chipsets right now. I am pretty sure that we will see 2GB devices eventually but all of them right now are 1GB. But frankly for everything you need to do on these units 1GB is fine, just like it is for most android tablets. And the quad core devices are very responsive and snappy, going from dual core to quad core makes more of a performance difference in experience.

>* video input for the factory-equipped backup camera

Pretty much every unit has a standard composite input dedicated for backup cameras which are activated with 12v on the backup signal line. They are all also able to show the backup camera before the system is fully booted, so you turn the car on, put it in reverse and you can see the backup camera while the android continues to boot in the background (15-30secs).

>* steering wheel controls (I'm assuming I need an adapter specific for whichever car I buy, probably not included with the HU but I want the HU to be able to accept them if possible)

A standard feature, and most cars are based on the same standard.

>* Decent sound quality output

I have found they have good sound output. Especially for playing MP3's. They also extensive audio controls and EQ capabilities so you can really tune the sound compared to most factory units of "Bass/Treble".

>* Good radio reception (does the US have an equivalent to DAB?) ... I'm willing to use an external FM module if that ends up being the highest quality option. App support is included in the word "good" here. And as likely figured out, I'm in the U.S.

Some say the AM/FM is more sensitive than their factory radio was. I find it to be about equal in my case.

>* Some SIMPLE form of external storage (SD card is fine, USB HD is fine, I even have a spare 60GB SSD with built-in USB port since I just rebuilt my PC)

Most units have a couple of SD card slots that can use whatever SD card size you want. I have a 32GB and a 64GB in mine. They also support whatever USB sticks you want to use on their USB ports. They maybe do not work with USB hard drives from what I have read, you would beed to research further.

>* Ability to tether to my WiFi hotspot (currently it would be a Nexus 5 phone) OR Bluetooth data connection (but I've found BT data sharing to be less well supported).

Most all support wifi tethering, but they do not support bluetooth tethering because the bluetooth is actually handled by a dedicated bluetooth card designed for audio/phone control.

>* Lollipop? I realize from searching there aren't any out there yet (pfft @ Parrot for nixing the aftermarket version of the RNB6) ... I'm not in a big rush to do the upgrade RIGHT NOW, if I can wait a few months to get a 5.x HU I will do that. Just need to know if such a model is known to be in the works?

Its a nice to have, but there are more 4.x devices in the world than their are 5.x and it will be supported for quite awhile. I am not sure what all it buys us anyway because 4.x is stable and 5.x new features really only apply to phones.

Basically, most all the current android head units are based on the same internal hardware designs, the and main differences are in the physical front panel layout of what buttons, or knobs, or if you want a dvd slot or not etc.. my recommendation is that you get one with the best options available right now which are a) quad core, b) 1024x600 screen res, c) 16GB internal flash storage. Other than those specs its all down to the physical design of the units front panel for the most part.

I chose the carjoying unit shown in this topic because I thought it was the best choice of front panel design(no dvd slot to waste screen space, at least one knob and not all touch(yuck), etc)... to fit in my standard double din auto.

http://xdaforums.com/android-auto/a...oying-rk3188-rk3066-2-din-head-units-t3193170