I agree with achoo. As a med student (which I went through as well) you want to get the most bang for your buck. Test both out and see what feels right to you. Aside from the frame and components, there are a lot of other things that will make a bike fit well (or poorly). Things like stem length, crank length, seatpost setback are a few that could affect this. Some you can fix later with new parts but it'd be a good idea to try to minimize the amount of "tinkering" you have to do to make the bike fit you well.

And try to go with someone who is an experienced rider... they'll be able to tell you pretty quickly if the bike fits you reasonably well (ballpark estimation).