First, UG does not prepare for Med. School. There is a huge gap in academic level, not even close. UG does not even prepare for taking an MCAT, everybody prepares for the MCAT with exception of few geniuses (frankly I heard of zero number of these).
Second, your own success in UG and strength of your Med. School application will depend strictly on you, not the college.
Might as well attend at school that fits you personally the best and having UG free / tuition free / cheap is a very good idea if going to Med. School.
You will definitely need to work much much harder than you have been (based on ACT 28). ACT is very easy test that does not determine anything but a level of preparation. ACT 28 indicates that the preparation was minimal if any. This will not fly in a future if one considering Medical school.