I was told by people at my school the following, not sure as to the accuracy, but just some impressions:
The University of Chicago is the class of the midwest and definitely the best in Chicago. Enourmous research potential and opportunity for fellowship placement. Drawbacks: nowhere near the patient volume as other Chicago hospitals. As one PD in Chicago told me, "They don't have a lot of patients but sure talk alot about the ones they do have." Also on the South Side, although by my accounts the campus area is pretty safe.
Northwestern: solid program, PD very helpful, happy residents; serves the "Gold Coast" i.e. comparatively more affluent patient population; everyone there seems to be really well dressed
Drawbacks: private attendings can make for some degree of disorganization
Loyola: good program, PD very nice and helpful, not really on the first tier with the top 2; operates on a firm system which can make for some interesting call nights when backup isn't that close by
Drawbacks: smaller program, less opportunity for fellowship
Rush: good program, attracts students from just about every academic level, some of your peers will be AOA/240+ step 1, others won't be close to that, the residents I've talked to seem to be happy
Drawbacks: not sure
Mind you, this reflects the opinion of a few people at a different university.