For best value, I'd go with an FX-8320. For gaming an i5-4670 can do well too if you're over clocking get the k version if not then there's no need for the k version. Both are very good processors in general.
Fx-8320 Bottlenecks it hard in most situations. You'd better go with i5 4670-90(k) and up for better gaming performance. i5 4590 is acceptable but it can reach about 80% Cpu usage in some games and might cause problems in the future.