If you intend to overclock, get the 8320, if not the 8350. If you really want to squeeze max performance out of the CPU, the 8350 is binned higher, meaning the silicon is better quality. You would be more likely to get close to 5 GHz on the 8350.
Either one will suit you just fine though. You should be able to hit 4.2-4.6 GHz on the 8320...the 8350 seems to be able to hit 4.8 GHz pretty regularly.
considering I don't want to overclock, I will go with the 8350