While CS + pre-med is a good fallback plan, CS in general is a hard major and will make it much harder for you to maintain the GPA for med school. You should definitely look at prestige for med school but I don’t think it matters that much for pre-med and CS will get you a good paying job regardless of the college’s prestige you go to. Have you considered the 6/7/8-year programs for med school? They are extremely helpful in streamlining your path to medicine (although it is highly discouraged to do a 6-year program because of the stress/workload).