Lou's definitely, imo. exchequer also has decent pizza, and hasn't been mentioned yet. You can't really go wrong with any of those listed - although Giordano's I would put on a slightly lower level than the rest.
My personal favorite is Heaven on 7 though. Mmm. The Jalapeno muffin is a must-get, and I usually get the chicken voodoo rigatoni. Not exactly "Chicago" though
