APUs vs CPU/GPU: Which one offers better gaming performance?

[Lily Adler]

Okay, I'm building a gaming rig and I'm trying to get the cost down to a little under $500 and to do that I need to go with a A10 7850K APU. The CPU and GPU I do want to use are the Athlon X4 and Radeon R7 370. The latter shoot me about $10 more, and the former saves me $90 at $420 which leaves me some wiggle room to crossfire with a R7 250 if I wanted.

So which one should I get and offers the best performance for the price?