We own BWV.
The advantage of owning BWV is the better chance of getting Standard View or Boardwalk View units. The biggest advantages to owning BCV is getting first dibs on 2 queens in the second bedroom - and having the home resort advantage for SAB - if you love Luna Park and are a BCV owner, you can hop - the opposite does not hold true.
BCV is a little closer to Epcot - I don't feel its significantly closer since we walk so much at WDW anyway, but obviously others feel differently.
BWV is a little closer to DS, but the walk to the studios is long enough that most people take the boat anyway.
BWV has guarenteed views, BCV doesn't - if view is important to you knowing you have a Boardwalk View might be worth owning there.
Dues have been slightly higher at BWV than BCV - I don't think significantly higher, but again, this may be critical to someone else.
The two resorts are close enough that BWV owners can take advantage of BCV restaurants and marina, BCV owners of BW's entertainment and restaurant - the BC Marketplace is a nice addition, but it wouldn't surprise me if BW added one eventually. If you feel strongly about being close to Beaches and Cream or the Boardwalk Bakery, that might make a difference. BCV has a kids club, BW doesn't - that could be another factor - though again, its my own feeling that the resorts are close enough for that to not be huge. YMMV.
BW is a little more integrated into the resort than BC. BC is a little quieter in atmosphere, and slighly more casual in terms of decor. I think BCV wins the ugly couch contest, but that is obviously a matter of personal taste - and is probably not important to most people.