Here's the verdict. Any i7 would runs circles around any FX processor. An i5 would be occasionally be matched with an FX series processor, but more often then not it won't be. It would be doing semi-circles around the FX processor.
Gaming wise, Intel has the superior processor. Before ADM fan-boys start to rant, I am 100% unbiased. All of what I'm about to say has been tested and proven.
An example being, if an FX - 8350 and a i7-4790k were to both play Far Cry 4 with ultra setting on. Despite the FX -8350 being an octa core processor and the i7 - 4790k being a quad core. The i7 would have substantially higher FPS. The i7 would have 60 - 100 frames depending on environmental factors in the game, while an FX - 8350 would struggle to sustain 60 FPS often dipping to the 30 - 40 range. (This is providing they both have the same amount of RAM with the same speed, and the same video card)
You get what you pay for.