Hi,
It really is based upon what you feel is best for you. In my experience...
UIC was my undergrad institution, it was my first choice for med school based on the student response being primarily positive about their curriculum. After being exposed to other schools, I realized that for me a smaller school would lower my stress level at least minimally because I would not have to deal with a more apathetic administration (this really turned me off). However, the ability of going for a dual degree would be easier here and at SIU than at Rush.
SIU is a very good school, I was there for a postbac program and the professors will give you as much or little personal attention as you want. For me, the PBL curriculum is not the best way to learn the material we have to know and I wanted to be closer to my family and friends as a support system. Carbondale takes a little getting used to, but since most of your time is for studying this isn't a huge concern, and there is always Paducah or St. Louis if you need to get away.
Rush has become my school of choice because I want to practice in an underserved urban community of Chicago, and their community service options are extensive, but in addition to that the administration is very supportive and my experience with the students there has been good as well. They seem more invested in training students from the beginning in dealing with patients and professors seem more approachable there than I felt they would be at UIC. The quarter system would be better than the semester system for my learning style as well. The cost may be high, but in the end it makes more sense to happy for the next four years getting to my goal than spending less and being stressed out the majority of the time.
I hope your decision gets easier for you once you choose Rush...(Sorry, I just had to put in a plug!) 🙂