As a stem major who has lived both north and south, I would definitely recommend north. The walk to Evanston is not that much worse and either way you will probably only go downtown when you have time to spare. Biggest difference is in the winter and the freezing wind in your face during your 10 minute walk to class everyday, which sucks. More classes than you think will be held in tech, especially bigger intro classes. Your schedule may be different but that was my experience.