on the one hand, a well balanced system i5 and lower gfx card would be better, as the higher offerings are usually aimed at 1600p/triple setups anyway, and, if you're gpu limited, you can turn the gfx down, but, if you're cpu limited, most likely the game just won't run no matter what (personal experience, when gpu is faster than cpu).
but on the other hand, although the MOAR CORES approach for amd doesn't quite work out yet as their per-core performance is bad, it might change in future as PS4 and most likely XBOX 720 too will have an amd cpu with 8 cores, so developers will finally spend time parallelizing the games, and the crappy ports(read: GTA V) should automatically run well on amd cpu's. Its not that intel will now be slow, it'll still be faster, but probably not that much. it's hard to predict though.