I figure I should weigh in on this debate you are having. This debate has been going on for at least 50 years or so. BC v. BU. Honestly, they are not very different once you leave Boston. I have had interviews out of state, and at times, they get confused as to which one I attend. (I go to BU) There is no question that in Boston, BC gets more respect. It always has, due to their alumni; most BC graduates stay in Boston and end up in Big firms around the area. Therefore, when BC students need jobs, their alumni seem inclined to go to BC and Harvard first. BU is right next on that list, but we don't have a strong alumni base in Boston.
Once you leave Boston, the two schools pretty much equal out. I think BU might be better for going into public interest while BC would be better for politics. As for large firms, I dont think one is all that much better than the other. From what I hear, you have to do the same at either school to get into a V50 firm outside of Boston (in Boston, it is easier for BC grads to get jobs).
The atmosphere is very different at the schools. BU desperately needs a new campus. I study at home becuase the library is horrendous. We share the library with undergrads as well, which is really annoying. The tower isn't as bad as everyone says, but most students just go to class and then leave becuase it is kind of uncomfortable to work in. BC has nicer facilities, but it is a little out of the city. My friends actually prefer it. I think you just have to see which campus you are more comfortable with.
Quick note, don't listen to BC kids or BU kids who trash the other school. No one can really compare their school to a school they dont attend. Let them tell you how their school is and then compare the responses with others from other schools. I didn't get into BC, but I probably would have gone had I gotten in. That being said, I can only give you an idea of what it is like to study at BU. You should ask a BC student what it is like there to get a proper perspective.