Which is better for gaming ? ''Processor''

Depends entirely on what you're playing and whether or not you use the integrated graphics.

In older 1-2 core games with a discrete card the i3 is better.

In newer multicore optimized games using the integrated graphics, the AMD A8 is better.

RE: Tom's CPU Hierarchy chart...this is old information based on testing with 2-3 titles that don't use all of AMDs cores. Most current releases present very different results. So it depends greatly on which titles you will play, how old they are, and how well optimized they are.
 

NormH

Distinguished
are you using the integrated card? if so get an a8-6600k its about $104 right now and is a decent cpu with better gpu than the i3. you can also overclock the a8 easily. if using a dedicated graphics card get a mid level i3 and a decent card like a 7850 or gt 650ti and you will be happy with either decision