Location aside any input into which program is stronger. Loved both on interview day. Fellowship matches are equivalent. Some say Penn has a better rep.

I have heard good things about both. I think they both have good reputations, perhaps Penn is a bit stronger, but not by much I think. However, there have been a lot of threads about Penn being a bit overly tough (I won't dare to say the "m" word, but it's been said), which I have not heard about Beth Israel.
So I would pick BIDMC, but that's just my personal bias. I only know 1 or 2 residents at each program well, so take it with a grain of salt.