theunliked :
Depends which i5 and which i3. The FX-8350 is almost as good as the i5-4690. The i3-4160 is around the same level as the FX-6300. They are both about the same in price.
in gaming the 8350 would fall between an i3 with hyper threading and in some games match a i5 4440.
overclocked the 8350 should be close to a i5 3470
an overclocked i5 always wins.
the 6300 is fairly close to an i3 3220, beating it when overclocked at 4.5 ghz.