(That's pretty strange how this is in the Antivirus section. 😛)
If you're not going to overclock and you're only willing to get either of those two processors, you should get the one that better suits the types of games that you'll be playing.
For example, the FX will be MUCH better for games that utilize multiple cores, but if your game only supports single or dual cores (most emulators, older games, etc) you'll get much better performance with that i3.
If price is truly a concern I'd actually recommend an Intel Pentium G3420 (2 cores, 3.2Ghz, 22nm lithography) and spend the difference you'd pay from your previous selections (here in California it's a $50 difference,) buy a MUCH better CPU cooler, and overclock the $h!t out of the processor.