If you are not going to be happy at NYU because you just don't feel it is the right fit due to any number of reasons, such as facilities, students, just overall vibe (NOT to say that any of these are problems at NYU, but just as an example), its going to be 4 long years...Now truly, the amount of debt that you could possibly face coming out is somewhat debilitating if you have plans to travel or work internationally where you might not make absurd amounts that you could here in the states, but medical school itself is an uncomfortable experience and so if you don't think you are going to enjoy the school, that lower debt load just wouldn't be worth it to me. Really take into consideration quality of life and where you will be the most comfortable and happy.
Either way, you're really not going to lose...like everyone said, you'll be living in Manhattan no matter what...and both schools are great schools. Good luck.