I guess I can't be totally objective about this since I didn't interview at Miami...I withdrew my application after being accepted to Florida!!!
Anyway, I do have a close classmate/friend that interviewed at both (he's going to FSU in the fall) and from what he told me, it's just going to come down to "personal" preferences. Both schools are well-known to be top-notch. Both encourage students to pursue THEIR interests. Both schools have LOTS of research & scholarship money. Both schools have excellent academic programs. And when I went to my interview, I saw PLENTY of diversity at Florida as well.
Basically, I think it really comes down to what YOU are looking for. Do you want to live in Miami or Gainesville? Do you have a spouse/family that needs to be able to find a job? Do you need to have the lower "state" tuition? Will you be able to find safe / affordable housing in Miami? What are your hobbies? Do you like to go camping or clubbing? Granted, there isn't a whole lot of free time in med-school, but when you have it, you'll want to enjoy it!
Personally, I would have been thrilled to have been accepted at either school, but since I'm married, I had to pick the school that would work for both of us...and for me, that was Florida (my hubby is Navy and will be stationed in Jacksonville).
Good luck in your decision...it's a tough one, but I don't think you could go wrong either way! Just remember to choose quickly...there's a LOT of people waiting on one of those seats to open up!!