If you've weighed both SCHOOLS the same as far as academics, then you need to consider other things. For instance, small town vs bigger city living. Cost of living. Distractions or lack of. How far will you have to commute. The commuting thing doesn't sound like a big deal, but it is. I live 30 minutes away from KCOM, in another small town. Time is your enemy in medical school. It's like money, there's never enough of it. You want to be as close to school as possible. I can't tell you about DMU, the school, but I've been to Des Moines several times. Nice town, lots of things to do.
Kirksville, of course, is way smaller. There are a lot fewer choices as to restaurants, bars, general places to go and see. However, Kville is charming in its own way.
If you are borrowing money, you need to decide how far your loan money can go in each place.
If your decision still isn't made over academics, then you really need to research that further. Get in touch with DMU and KCOM students via this forum (there are TONS of KCOM students on here, myself being one of them). Ask each the same questions. Ask what they like and don't like.
Good luck with your decision.