I would say that if you are interested in biotech Stanford would be the place to go. Not a Stanford medicine student, but I have quite a bit of experience with the SoM and I can confidently say that students are pretty engaged and close among each other. Also, there are plenty of opportunities to do internships at Genentech or any of the big biotech companies here, or any small ones too.
The weather is truly wonderful, the campus is GORGEOUS and the facilities at the SoM are really nice. The student learning and teaching building is incredible and very fancy/modern/new, there is a really nice student lounge that facilitates socializing, housing is MUCH better than Harvard's, and Stanford just opened an amazing new hospital (seriously, it is incredible go look it up if they didn't showcase it during interviews/2nd look).
Full CoA is also something not to brush off. Full tuition at Harvard would still mean ~80 - 120k in loans for cost of living (depending on how frugal you are), and that can really add up with interests. Going into residency with no loans sounds amazing IMHO. From Stanford you will have no trouble matching back in the east coast or if in the west if you choose to.
Can't go wrong with either one, but full CoA at Stanford would be hard to pass.
Only negatives are that Palo Alto is pretty boring (could be a positive if you don't mind the suburb life), and patient population at the main Stanford hospital is indeed not very diverse (there are opportunities to engage with a more diverse population through the free clinics and doing rotations in Santa Clara IIRC).