If you are building a PC that will be used strictly for gaming then without question; go with Intel. Get a processor that you will actually utilize such as the i5-3570K. In fact, for gaming, anything outside the 3570K is wasteful. I would suggest dumping your money into monitors and/or multiple video cards rather than an i7 processor which will game no better than the i5.
The FX-8320/8350 are not terrible chips for gaming as the majority of games will be video card dependent with some select titles being both video card and processor heavy such as Skyrim. It is in these select games that Intel chips will separate themselves from AMD processors.