Also. do you want a car? don't live in boston. Parking is ridiculous and expensive.
These are simple little things to consider outside of the program. If you like both programs equally these types of things might help you make a decision.
What is the total cost of both schools? (including living, transportation, etc). I really think you will be prepared wherever you go (as long as you do what you're supposed to). $$ should be a big factor, unless you're not paying! I have also heard a few negative things about preparedness of students from UPENN, maybe look into this, talk to some tstudents, etc.
Try posting on the dental forum?