I think you have a pretty good idea of the choice that is facing you... I don't think either school is per se better. It will pretty much depend on your preferences. The schools are in VERY different parts of Boston. BU is urban and BC is suburban. I attended BC undergraduate, but BU was my choice ahead of BC for law school. In my opinion and this is just my opinion I felt BC law was a bit of a "drink the law school kool- aid" type of place, where as BU was a little bit more eclectic and diverse. On the other hand what I felt to be shall we say overly conformist attitudes at BC many others see as collegial.
Having friends who are about to graduate at both institutions and speaking strictly from their expirences ... my friends at BC law have had an easier time finding top quality jobs, both at graduation and summer associate.
Good luck, but both places are great schools I don't think you can really make a wrong choice here.