Are you on a budget here?
From the AMD side, you can get an FX-6350 and overclock it or you can go with the FX-8320 / FX-8350.
From the Intel side, the i5 3570K or i5 4670K should do just fine. Of course you can get an i7, but you can stick to the i5 if you're solely going to game.
Again, it all depends on your budget.
Best of luck.