I'm biased as well, as I will most likely be attending Tufts Med this year. These two schools are pretty similar. Both are expesive, both have decent reputations, both in major cities, both will prepare you clinically. Therefore you have to look at more subtle differences such as
Curriculum, facilities, research opportunities, etc. are some of the differentiating factors. Here is my analysis on this (I'll be as objective as possible).
Curriculum- Tufts has a very advance & integrated curriculum. About 1.75 years long (which gives ample time for USMLE studying). It's P/F I believe as they changed it. They have the TUSK system which they pride themselves on a lot as well. Again I know nothing about Georgetown....
Facilities - I think this is where Tufts has a clear advantage. The facilities are pretty much brand new everything. I heard Georgetown was a bit run down (from some people on SDN).
Research- I believe Georgetown is a bit more researchy than Tufts. I think both have similar NIH funding, but GT probably emphasizes it a bit more than Tufts. I felt Tufts was more focused on public/global health and community service. The opportunities are still ample at Tufts but take this for what its worth. GT's location helps as well.
Location- I interviewed at GWU in DC. And I personally liked Boston a lot more than DC. Again this is a personal preference. So it's up to you.