I like ATI a lot. I had experiences with Nvidia, and they're not bad either. The only thing I hate from ATI is that the setup needs .NET Framework...but I use the manual install way
A thing I hate from Nvidia is that they make releases and releases of drivers...why? I dunno. Another thing is that they run hot.
In my rule of thumb, I also enjoy the ATI chipsets...or AMD. I think they're using AMD Chipsets now...not sure
I think AMD still makes ATI chipsets.
But, in the rule of combination, Intel with ATI, and AMD with Nvidia.