Perplexed,
I can tell you a few about those schools except for U of B. USC changed their program to PBL (Problem Based Learning). THis year they changed their entire curriculum so it seemed kinda disorganized. You might have to get some time to get used to this. I'm not sure if this is for me because I think I'd rather sit in a lecture. Plus you're in a cell consisting of only 24 people all four years and you're only with those ppl all 4 years.
As for UCSF, I think it may be really difficult for you to get in since you're Canadian. They mostly favor in-state residents, but from what I hear, they have a solid program (esp. research).
For UOP, they have an excellent clinical program. Most ppl worry that an accelerated 3 year program is going to be impossible, but I know many who have succeed in their program. Their facilities and ppl are extremely friendly. They only have ortho and oral surgery though for specialty programs. It's great if you just want to do general dentistry. Plus they have a a famous speaker that teaches their practice management, unlike many schools who don't focus on that very much.
U of Penn had the best program I've seen in all the schools I've visited. They are a very academic school. They have hospital rotations as well as international externships available for those interested. I think this the only school or one of few that actually allow you to do oral surgery as undergrad dental school. THe only downfall I saw at Penn was their facilities. Everything was just really old. You spend the first two years in the basement. However, they have one of the best (probably like #1 or #2) in getting people into their preferred speciality. LAst year they had 11 people get accepted to an Oral surgery program and 7 into Ortho. So I guess if you really want to specialize, then Penn is a great school to go to. I think they must be doing something right because they are turning out pretty solid students.
Good luck. IF you have any further questions about any of the schools I've talked about, I can answer or elaborate more based on my experience. I still have my interview at UCSF, so I will let you know how that goes!