How would you be paying for each one? The first thing to consider is probably a rough financial limit - you probably don't want to go over the cap for federal student loans (~28k total), and you also don't want to put undue strain on your family/yourself (like if they would have to make lifestyle sacrifices, or you would have to work multiple jobs year-round). If both pass this checkpoint, you can move on. Basically, if the difference between the schools is that at one you'll have to pay out 40k that you could otherwise use for med school, it's less big of a deal than if the difference means at one school you'll need private loans that your parents won't cosign for, or at one your family has to live on ramen noodles to help save for tuition.
If both options pass the financial viability check, I'd go with Northwestern for sure. Undergrad is a really fun, exciting, and unique time in life, and one of the main reasons why is that you're living with your peers, who can push you and broaden your horizons. Students at Northwestern will be really accomplished, motivated, and come from a very diverse set of geographic and cultural backgrounds (UIC is great too, but NW is on a different sort of level). College and the dorms sort of facilitate an egalitarian social environment and allow you to come into contact with a a huge network of people, which doesn't ever really happen again. Having more time at the school will also allow your to take more classes and explore more interests, and long term investment in clubs/activities/research experiences is more rewarding and can only help your app when the time comes to apply to medical school. The only real negative would probably be some more rigor at NW (a lot of students at top schools whine about perceived grade deflation).
In comparison, being a commuter student (and on top of that, a commuter student at a place you don't like so much) really doesn't sound at all appealing. I see why you'd consider that option and I know some people go that route, and it seems like it could be nice to get to med school two years sooner. And if it's your only option financially, you gotta do what you gotta do. But honestly, I'd say the traditional college experience and spending time in a place that you're interested in and excited about is priceless - it's great to plan things out and deferring present happiness is absolutely a source of securing future rewards, but for the big things, it's also good to live in the here-and-now and seek happiness in the present.
