Best for gaming? the better the video card the better performance in games, you should consider an Intel build if it's for gaming with an i5-4670 or even an i3-4130 will give you similar performance the FX-6300 would give you, with the difference that with Intel you'll have a nice upgrade path up to an i7-4790k whereas with AMD you'd be pretty much on the top already.
Rendering, virtualization and such however would benefit more from the 8 cores the FX-8320 offers.