First let me say that I have a strong bias for Android devices. I find Apple products extremely restricted and their interface is quite boring.
I have an HTC EVO LTE, it's from the One X family so most of the internals are the same. It just also has two upgrades (micro-SD slot and kickstand). I can't really comment on One X build quality but the build quality of my Evo LTE is top notch (a big reason I chose it over Samsung).
Screen: The display on these is simply stunning. The best way to describe it would be one of those demo phones at the store with the fake screen.
Camera: The One X line added a dedicated image chip for the camera and it really makes a noticeable difference. This wont replace a DSLR but it will easily replace a point and shoot.
Battery: I was really upset to find out HTC went with a non-removable battery for their One X line. I was coming from the original Evo 4G which had a horrible battery that I replaced with an extended one. My new HTC battery last much longer than the extended battery in my old phone. They did a great job in correcting this problem.
Processor: Due to some issues with LTE, the US release contains a 2-core CPU instead of the 4-core found in the international version. However, there's plenty of benchmarks floating around to show that this is not a limiting factor at all.
OS: Android 4.0 has been impressively stable for me. They have fixed a lot of the bugs from 2.3 (phones) and 3.x (tablets). HTC has their own layer called Sense. This is more just eye candy but really nice eye candy at that.
Off topic - It amazes me that less than 2 years ago I purchased a Dell Mini9 netbook and the phone has more processing power, ram and storage space.