The two school are at a contrast. Harvard is very research oriented and many breakthroughs in dental materials are from Harvard graduates. There is much money in this, but it's not the same side of dentistry that I personally find so attractive. I managed a volunteer dental clinic after Katrina in New Orleans and worked with 100s of volunteer dentists from many different schools. (I know I'm bound to offend some people, so sorry) From my experience UoP produces outstanding dentists without a small percentage of graduates needing for a GP residency. The 2 Harvard graduates I met worked for insurance companies and had some of the worst doctor-patient interaction I have seen (NYU grad.s were the absolute worst IMO). Both Boston and San Francisco are on equal playing fields when it comes to the charisma of the cities, but you cannot put a price-tag on time. Depending on how old you are, the 3 year program may begin to weigh in on your decision, getting a year back out of your life.
One thing to note, I always thought it was funny that nearly every dentist would tell me that their school was the number 1 school for dentistry, including Harvard, North Carolina, San Antonio, Creighton, Tufts, NYU, UoP, UCSF, UCLA, and Loma Linda. In my opinion what makes a great dentist is their ability to solve problems and make the patient feel comfortable while doing it. UoP produces better dentists than Harvard. If you'd be interested in product development, discovering the next Xylitol, or dental robotics, then go to Harvard.
I would choose UoP.