I would go for the i5, in my opinion it is excellent. I have the i5 3570K, it is one of the best value for money CPU's out there.
For the things you do it would be perfect. The i7 may be a waste of money as the larger price tag is for the hyperthreading technology, which games don't need or run (it's only for serious editing and graphic design).
And basically i5 is more powerful and efficient than the AMD. For you I would go for a good i5, it's perfect for gaming and other tasks
Here's a comparison: http://www.cpu-world.com/Compare/435/AMD_FX-Series_FX-6...