Dave, my personal preference is: FX-8370E > FX-8370 > FX-8350 > FX-8320 > FX-9370 > FX-9590.
The FX-8320E would probably go right after the FX-8370 models, however I cannot comment about it since I have not tested one personally.

Go for the FX-8370E if you have air or AIO cooling.
Thats the best model to do some tinkering with too