The Intel® Core™ i5-2500K and the Intel Core i5-3570K are maybe the best performance/value gaming processors that you can buy right now. Around $220 it is hard to beat the performance.
even the lowest end i5 2320 will beat the pants off an fx6100, especially for gaming. An i5 2320 will beat the pants off even an overclocked fx 8150 for gaming.