PicSay Pro is excellent. Photoshop Express was okay. Photo Enhance Pro was ok, as well. There are a ton of other apps for doing fun things with pics, like Paper Camera and Pocketbooth, but for just performing normal photo editing I use PicSay Pro all the time.
Another Pic Say Pro vote. And the basic photo editing (auto-fix, midtones, highlights, lowlights) in stock ICS "can be" a great compliment to PicSay. (not always on the auto-fix)