Well for one I am tired of the "big school" environment. UIC is a great school that gives tons of hands-on work, but I think that I want a supportive environment that is a little more close-knit which I feel UIC doesn't have. You seem to have to find a group and make ends meet that way. Rush really promotes the small community/family environment at the school.
Northwestern is a wonderful school in a great location, but I feel that I will not get much hands-on work in the first two years. Also, the price is quite high...
Loyola is another great school but it's outside the city which would require me to give up my apartment and move out there. I live about a mile away from Rush.
Overall, I want a small school environment, I want hospitals/clinics that are going to be able to give me some opportunity to interact in my first two years, cost is reasonable, wouldn't require me to pack up all my things and move, etc. The other things that have drawn me to like Rush: brand new hospital, great location (for my living situation and just where it is in the city), intense curriculum, friendly environment, several recommendations from my personal physicians, great hospital system with a plethora of residency opportunities, participation in community clinics, cost is reasonable compared to others