[AT&T, Rogers HTC One X, Telstra One XL] ECEXCURSION:
I own both phones. I've had the One XL since launch day (1 year, 9 days ago) and I bought the One a couple of days ago as a replacement. Perhaps I can shed some light on the differences between the two phones for those of you who are considering one of the two. Sorry for the long post, but I felt I should be thorough. :)

HTC One vs HTC One XL Comparison

This is just a strict comparison about random aspects of the two phones... There isn't really any order to it; it's more of just a long rant about the differences. I'll start off the comparison in my favorite way - looking at what's wrong with the new device.

Cons of the HTC One:

Physical Design: Since the plastic sides of the silver phone is white, the whole aluminum body looks white if you give it a quick glance. I hate white phones with a passion but aluminum is my favorite color so it's a trade off for me. Of course, this is a personal preference and will vary depending on the user. Other items regarding the physical layout of the phone include the size. The One is the same width as the One XL but it is slightly longer. If you were to take the One XL and add on a second row of capacitive buttons they would be the same size. Personally, I feel that the One's "aspect ratio" is better, but the phone is kind of long for my tastes. The iPhone 5 is a better size in my opinion, but again, this is just personal preference. Another thing that may or may not be of concern to you depending on whether you use a case is how easily the phone slips into your pocket. The One has sharp edges (similar to a macbook) so it doesn't slip into your pocket as easily. Similarly, since the edges are all made out of aluminum the phone will dent if you drop it on a hard surface. (So don't drop it)

Capacative Buttons: The One only has 2 capacitive buttons compared to the 3 that the One XL has which is super annoying. HTC did this to comply with Google's design guidelines but other manufacturers *cough* Samsung *cough* have ignored this suggestion. They should have made the HTC logo a capacitive button as well. The touch pad doesn't fully extend that far off the screen, so even with a custom kernel the HTC logo only works "sometimes" as a button. I believe this is an engineering problem that could be attributed to AT&T. The HTC logo is not clear and it does not light up; it is painted on underneath the screen - the same as the logo at the top of the One XL's screen - in metallic lettering. If they had put a capacitive sensor above the logo it would constantly interfere with the metallic paint (This is my personal theory, but I think it's sound).

Another disadvantage of the One is the software isn't as mature as the One XL. The One XL is at the peak of it's development cycle; there are very few bugs and everything has been optimized. The One is new to the game and we're still waiting for HTC to release new kernel sources along with everything else. Developers are still trying to figure out how to work with the phone. The developer of the ROM I use, for instance, doesn't even own the phone yet!

Carrier Loyalty: As with the One XL, AT&T gets special privileges. AT&T is the only carrier who gets a black HTC One. They're also the only carrier who offers a 64GB version (The Developer Edition also has a 64GB version but it is only offered in silver).

Pros of the HTC One:

The HTC One isn't all bad though, not by a long shot. It has many numerous advantages over the One XL.

3rd Party Support: One of the best things about the One is that the phone is standardized among all carriers. You can buy a case in the Sprint store and it will work on your T-Mobile One. Additionally, all GSM phones (International, AT&T, T-Mobile, Developer Edition) can flash the same ROMs without having to worry about bricking the device. In many ROMs you just select what version you'd like your phone to be optimized for. This helps with development immensely! I'm so glad HTC did this. Supposedly the One will also be HTC's only flagship phone for this year, so you don't have to worry about an HTC One+ coming out in 4 months. I'm also very pleased to see that every carrier has put out advertisements for the One. I've seen many of them all over TV and even some in movie theaters. This is where HTC messed up last year. Unless the individual phone sells well 3rd parties won't make accessories for it.

The only real difference between the GSM variants is that the T-Mobile version includes more radio bands. Thus, if you want to get the most versatile version like me, get the T-Mobile version. It's also unbranded so it has no logos (aside from the "beatsaudio" logo on the back which the One XL also has)! :D

Physical Construction: The HTC One feels very solid in your hand thanks to the "zero-gap" construction. This means that the entire back/sides of the phone are all one piece. The plastic accents are all bonded to the aluminum backing, so it is similar to the One XL in that regard. Because the aluminum and plastic is CNC'd out in one piece you can consider it as a single unit; you will never feel the plastic injections with your finger unless you have a defective unit. It's somewhat similar to the unibody design of the One XL minus the speaker grills which are separate pieces - you can feel the transition between those pieces and the screen. This is normal.

Audio and Video Recording: The recording quality of the One is indisputable. It is simply superb. You can record video at a night club and actually enjoy the music and video afterwards. The microphone is insanely good. The video camera is designed to excel under low light conditions. One consequence of this is that the One's camera is only 4MP (slightly higher than 1080p) instead if the XL's 8MP. This means that the camera is great for what most people will use it for, but unfortunately I can no longer carry around my phone as a dedicated camera replacement (for vacations and things where I want a little better picture quality).

Performance: The One is FAST! Using 3DMark's new application you can test the gaming performance among various platforms. The HTC One GPU is actually more powerful than a nVidia 7900GS videocard (think precursor to the 8800GT)! I actually had one of those in my gaming PC a couple of years ago. To me this is insane. To think that my phone is more powerful than the higher-end gaming PC I built in 2006 (in some tests).

Battery Life: The battery life in the One is pretty good. I'm getting around 4.5 hours of on-screen time but I'm still tuning the phone. I've only had it for 3 days. The battery isn't even settled yet. I'm sure in 2 weeks I'll be seeing 7+ hours on-screen time once I get everything sorted out.

IR Remote: One small thing that no one thinks of is the HTC One's IR blaster integrated into the One's power button. You can now control all of your home theater equipment using your phone. This is very handy for people like me who always find themselves on the couch with their phone in their hand but don't want to take the time to search for the remote. HTC even includes a little TV guide app that lets you select a specific show and it will automatically change the channel for you. I like this!

Fixes from other Phones: The HTC One's notification LED is fixed from the One XL. It is bright and you can actually see it from all angles. The HTC One XL has an almost useless notification LED and can only be viewed when looking from the phone straight on. I once had a coworker stare at my One XL for 2 minutes before he asked me whether something was blinking. He thought it was but he wasn't entirely sure. The One has solved this very annoying problem.

Storage Space: The One has much more storage space than the One XL. The 32GB version has about 25GB of usable space where as the 16GB One XL only has about 9GB. This is nice if you're thinking about replacing an MP3 player or like to have mobile videos stored locally.

This is all I can stand to type for now. I'm sure I forgot stuff but I'll have to wait until I'm at a computer to finish the comparison. If you liked the review click thanks please. :)

Sent from my HTC One, edited on my laptop