Integrated Intel Graphics work best out of the box with open source drivers. (Guessing you are going to use a i7 Ivy Bridge CPU, and that should already have Intel HD 4000 graphics built-in depending on which model you pick. They are pretty decent graphics built-in with no need to buy a discreet card.)
»
www.phoronix.com/scan.ph ··· ge&num=1Nvidia has the best proprietary driver support.
If you are going to game though, I would recommend a Nvidia GeForce GTX 650 or higher. You might could get by on the Intel graphics though, really depends on the type of games you are looking to play.