Honestly the difference between NVidia and AMD (ATI), isn't radicle... it's mostly based on preference. Lately though, it seems Apple has been transitioning most of the mac line to AMD graphics, so that automatically means you'll have better support with them. As for CUDA, it's basically a set of drivers needed for NVidia graphics cards. Progress has been made to better support NVidia chips on hackintoshes, but if choosing to go that route make sure you do your research, for some - Fermi - cards have stability issues with Mac OS X.