It really depends on both your budget and what sort of games you'll be wanting to play. For instances, with AMDs new cards they have Mantle, this allows the GPU to talk directly to the game, instead of going via an API such as DirectX 11. This means a faster experience in games like BF4 and some other upcoming titles. On the other hand, as mentioned before, nVidia generally have better and more stable drivers. nVidia are also releasing shadowplay later this year which will be quite a cool feature. So if you're ready to play top dollar, I'd go with nVidia. However, if you are on budget, (especially if you are looking to play BF4) I'd go with AMD.