These are good questions and having gone through this last year, and now being an intern at UIC Med/Peds, here are a few of my thoughts:
Depending on what you want, each of the programs is slightly different. U of C is the only program I don't know much about as I didn't apply there for 2 reasons: 1. restructing of Medicine programs with many attendings leaving and 2. lack of adult public patients (and lots of criticism in general about how U of C handles public pateints). I come from a well-known med school and had very competitive board scores, but was interested in seeing public patients with a mix of private. The only two programs that allowed this were Loyola and UIC.
Rush: 84% private, 16% public, limited options to be at CCH. Outpatient clinic was very small, has great peds but many medicine patients are covered by private attendings instead of ward teams (or are co-shared with less teaching for residents). Also heard that the new hospital is mainly for surgical patients, will not benefit Med-Peds, but unsure if this is accurate info. Overally, did not feel like it was right for me, also very poor turn-out at the interview dinner so couldn't even ask residents questions.
Loyola: Great peds, wonderful mix of public/private closer to 60%/40% including having a VA, but over half an hour outside of the city. Medicine program was also much smaller. Felt like if I was going to be that far out of the city, I might as well rank other cities higher with programs that I liked more. Overall, a very well-run program with great board pass rate and friendly environment. The PD was also a lot of fun! Overall enjoyed this program but felt that location and size of medicine program were limiting factors. Residents were nice, too.
UIC: Great mix of public/private with a VA. Having now been through the VA (which UIC shares with Northwestern), I can't imagine not having one--excellent teaching, great resources available to patients, wide variety of cases from bread and butter to the extremely rare. Med Peds outpatient clinics are brand new and amazing, good clinic support staff. Medicine program is large, great PD, residents are very autonomous, fellows do not run the show so lots of hand-on resident learning, very adamant about great morning report and conference teaching (which I did not realize is HUGE when I was interviwing). Peds side is smaller, now that curriculum is revamped lots of excellent teaching, new faculty is very involved, some subspecialty peds are run by attendings that are both at RUsh and UIC (so essentially the same attendings). There is every peds subspecialty with rheum faculty recently being brought on. Board pass rates are higher than national average (I believe 100% for past few years but double check on this). Our Med PEds PD is incredible, really the greatest PD I met while interviewing. Lastly, the Med-Peds residents are really friendly and make an effort to support eachother, which went a long way for me. I can say that now that I'm in the program, I am lucky to have ended up with such a good group. Intern year is hard and things like location/colleagues really matter a lot.