NIU recently announced an initiative to attract top students, both in-state and out-of-state, and has been making some significant merit awards (Illinois directional increasing merit aid
). With a 28 ACT you're well above the curve at NIU, which has a middle 50% ACT range of 20-24, so I would think you'd be a strong candidate for a significant merit award.
As m2ck notes, there were "issues" with MAP grants - the major non-federal need-based aid available to Illinois public college students - this year. The issue, which has persisted for several years, is that the state does not have the money to fully fund the program, which means there are many more students who qualify for MAP grants than actually get them. The program is administered on a first-come, first-served basis. This means that the students who get their paperwork in early get the full amounts they qualify for. When all the money is gone, nobody else gets anything. This year, the well was dry in mid-March. So if you do wind up going to an Illinois public college, get your MAP grant paperwork in early.
You'll find that the two schools have very different environments. UIC is an urban campus, with all that entails, positive and negative. DeKalb, on the other hand, is a small, rust belt city, that pretty much revolves around the university.
I don't know any details about the psychology or science departments at either school, but I am confident that a motivated and engaged student can get a top-quality education at either. What you do when you get to college is a lot more important that what school you go to - so your college choice should be based on finances and "fit." You can get a good education almost anywhere, if you apply yourself.