X should have the best battery life cause the thing is ridiculously huge, at what point is a phone not a phone anymore? It's almost like carrying around a PSP with you all day. (Not quite but its huge).
I Have the incredible and have zero complaints about the phone itself, verizon and the recent update to the android software, thats a different story. My battery life was much better untill the last update to 2.2 or whatever it is now.
If you have a charger in your car though you will never really have an issue. I manage fine and just plug it usually once a day for an hour or so.
No comments on the other phones as I have no experience with them.