FX-8320 (Stock) or an AMD Athlon X4 750K (OverClocked)

are you looking to build a system, because those two chips are different sockets, so if you have a system you are upgrading, you might need a new motherboard.

The 8320 should perform better. I have one and it rocks everything I throw at it.

If you are building a new system, follow the new system sticky and post your budget, location, etc and the users here can try to help you build a complete system.