You might want to ask on other forums. Med school forums get more traffic, and they are doing the same thing with loans that we are.
Also, if the school loan thing goes through congress ( i think it just did?) then the govt will not be using third parties to disburse loans, they will be basically doing it all themselves.. So in a few years, us treasury will be your only option anyway. Us treasury offers no special deals, whereas I hear banks will sometimes offer you deals such as points off of a car loan or home loan, or maybe freebies like free tickets of some kind (plane, event, ski, etc), maybe free cash or a free checking or savings acct or the like. Not sure if they're still doing this. If i were in your shoes I'd just call around and ask the banks what they can offer, and go with the one who has the best freebies. If they're just servicing US govt loans, your payment terms, disbursement terms, and deferment/forbearance options are going to all be roughly the same anyway. The banks cant offer you much more than points off your disbursement fee and freebies.. the other terms are set by the govt and are standard across all service providers.
I went with us treasury because the process was super easy and I was able to do it from my couch. They also have a well staffed service center, and have NEVER had a problem waiting on hold when talking to them.