I too find ATI cards (due to the drivers) far more problematic. I could care less if I get more performance per $ with ATI, which is the case right now, there is just too much wrong with the ATI philosophy about driver support.
ATI drivers are such a joke they never even fix glaring problems when the next series comes out, they just assume you will buy from them again. I still have servers I can't even uninstall the Rage Pro driver from, motherboards where it wouldn't allow setting custom resolutions, and people telling me I need special driver cleaners because they can't do a proper uninstall routine.
It's outrageous, even moreso that people try to imply this is as good as nVidia for many years.
Game bugs are a different matter, I do agree ATI has gotten more agressive in fixing those.
I'm no fanboy of nVidia, I am just against going through BS to get ATI software to work properly. Since most people seem to disagree, I've love for nVidia to pay me (lol) but then I wouldn't say a word as it would then truly be biased instead of a plain factual statement that ATI drivers have been much more problematic for me and my customers. The shame is, the opposite seems true of the hardware itself, I like ATI hardware more and the nVidia bumpgate fiasco left a bad taste in my mouth. Then there's Intel, far better debugging and the market leader. We need the more responsible people from these three companies to leave them behind and start a 4th video card company.