If you truly are pursuing med school, go to a school where you would be the happiest where can get the highest GPA. Since undergrad is not the final destination, you may have to swallow some pride and go to a school that may not be the best one you get into. Med schools value GPA over the institution you come from. Furthermore, med programs are notoriously difficult to get into, like >5%. So if you know this is what you want to do, find programs at schools that feed you directly into med school after graduation.