Like others have said, AMD hardware i cant fault, but everytime ive been with AMD, i buy a game day of release, and find the game has problems, either sub par frame rates, stuttering or other oddities, which either dont happen on Nvidia hardware, either because the drivers are already out, or beta drivers were released either before or not long after the games release.
For example recently i had a 4870 in my system, got BF3 day of release, it ran like shit, even on 720p Low settings. Swapped in an 8800GT, it ran significantly better, 720p on Medium was quite playable, on Low no problem whatsoever. I recently put the 4870 back in, and got the latest drivers, and finally the game is playable at 1080p Medium. Yay ! But if i had stuck with Nvidia in the first place, i wouldnt of had this problem and would just have had happy gaming for whatever the time from release to the new drivers was (2/3 weeks ?).
I want AMD to get there shit together, because there hardware is powerful and the cheaper equivalent to Nvidia, but the drivers just make my fun time shitty :/ I shouldnt have to wait nearly a month to play my game "properly".
Yes, Nvidia fucks up on games too (Dragon Age 2 for example "Up to 516% in Dragon Age 2" LOL no Nvidia, you mean it finally runs properly), but from my own experience, its usually a safer bet for more games than AMD, either because it works day 1 or is quickly fixed with a beta driver (which, i still dont like, but its better than AMD, who i dont see releasing nearly as many beta drivers as Nvidia).