Stayed at both, like both. They are essentially 2 halves on one big resort -- with shared amenities, like pools and fitness center.
The pool is in the middle. They share restaurants. They have their own bus stops. YC is closer to the ferry boat dock (and DHS) and BC is a shorter walk to Epcot. But the buildings are attached to one another -- so I don't find one more convenient than the other.
YC has full balconies, BC it's more by request. The room decor is a bit different, although the rooms are basically the same.
YC has a more elegant (and much quieter lobby). BC has the big buffet downstairs (hence the more crowded and noisier lobby mornings and evenings). I'm happy at either one -- I tend to choose based on which one has a discount available or the room category I want available.
If you go on the YC/BC thread, you will find that people have definite preferences, but it's based more on decor -- there are lots of photos in the beginning that might help you decide. But don't worry too much -- they are both great and I would be happy to stay at either one again. The likelihood of a full balcony pulls me over to the YC side most of the time.
Hope this helps!
