Passmark has a large portion of is tests based on visuals that is likely what brings the a6 so high in the charts. I was looking into the exact same thing as you not too long ago (a6 3400m vs 2310m), except I want to do some gaming. The only review I found that was useful is from tomshardware. It compares the A8 3500m to a i5 2420m. If you flip through the pages you will see synthetic tests going one way or the other. Gaming tests favouring the A8 and application performance favoring the i5.
LINK
You really wouldn't go wrong with either, but IMO the i3 better suits your needs.
Since you specifically mentioned Photoshop I will put those pics here from the tomsharware review to show you my point. Again, these are for the A8 vs 2420, but they scale similarly.