Where is your incase rubbing against the screen protector (bottom, sides, top, or just all around)? I've heard of some people sanding down their inner lip of the incases, since it's a bit too thick, which solved the rubbing issue.
In terms of getting the most vivid and clear screen protector, look into this one:
http://store.apple.com/us/product/TN612LL/A
It's a little expensive, but it's probably the most clear/vivid screen protector on the market.