I think that while lots of people tend to procrastinate in College it is not a wise way to achieve academic excellence. I would pick either UCSD or UCSB if medical school is your goal. I see lists of medical students at UCSF and UCLA from time to time and there are always some from UCSD and UCSB but I have never seen anyone from CalPoly although I am sure there must be a few. I might tend to favor UCSB just a little bit because I have visited UCSD 4-5 times and UCSB twice over the years and the students have always looked stressed out at UCSD. Students I have met from UCSD corroborate my impression. Cal Poly is a good school and everyone I know who has gone there has loved it. Unfortunately you are a California resident so getting into medical school will be challenging so you want to attend the best school you get into and excel.