Water ice in Philadelphia

If I were going to be in Chicago for a day and could only have 1 Italian ice, I'd go to Mario's. Well, I'll be in Philly for a day and can only have 1 water ice. Any recommendations (a search for previous LTH threads yielded no results)?

Extra points if it's open late enough for me to stop by after a Thursday or Friday night Phillies game, but no problem if that's not possible.

There's this thread on Chowhound. I've been to Little Zesty's in Manayunk; it's quite good.