Hard choice i must say - you have already got a motherboard for the 8320, so no real benefit of not going amd again other than better single core performance.
If affordable, the 4690 will be better. You say you mostly do gaming, so the 4690 has a benefit there, most games are very bad at using 4+ cores, or even 2+ cores. Thats where the i5 shines - its single core performance. The 8320 is better at multithreading though, and might be better at something as streaming. I would say - If you only care about gaming performance, and upgrading cpu is the only choice instead of gpu, go for the i5.