Adding West Virginia or even Rutgers to the ACC, instead of BC, would have made more sense to me in terms of athletic rivalry. Of course there are opinions that have been conveyed to the contrary.
Alot of folks in upstate SC would have preferred WVU over BC and SU. They see WVU as more of a school like Clemson and VT. In addition, it would have helped to keep the ACC more 'regional'.
If you ask UVa or Duke or Wake, then BC is a great choice (geography aside). BC, an excellent, small private school and should fit right in with them.
I tend to think BC 'might' have an easier time fitting in because they already have about 10-15 years of annual athletic games/meets/events with Miami and VT.
It just really depends on who you ask.
Geographically (Philadelphia), and even travel wise, Temple would have been a great addition to the ACC as #12. But as well known, and many have posted about, the school draws very poorly in fb, has too many recent losing seasons, and has the negative stigma of being booted from the BE. Temple does have respected bb though.
If the ACC could have had anyone in the 'NE', they best choice would have probably been PSU (if hypothetically they were available). They would be a good geographic fit with the 'northern' ACC schools. In addition, PSU is still one of the most popular schools in the NE, despite being from such a small market as they generate thousands of alumni every year.
AS someone already mentioned, they are a huge state school though and they wouldn't sit too well with Duke and Wake.