Upon second thought, I don't think either school really has an advantage over the other. I mean, they are both top notch. UChicago has its advantages being in a big city and having a good match list. UMich's curriculum, however, is one of the best because it has P/F, some PBL, and an organ-based approach. But UMich is in dreary Ann Arbor, but then again, it's in the middle of a huge undergrad campus.
Basically, I would be happy at either school. Too bad I don't have the luxury of making this decision. Hopefully I will.