I don't think you can go wrong with either - both are great resorts!
DH and I (and my parents) just returned from a quick stay at the YC last weekend. It was our first time at the YC, but DH and I had stayed at the BC last August. Being that we don't have children yet, and based on others' opinions here that I value, I was fully expecting to prefer the YC.
While we enjoyed our stay (no issues to speak of and the resort CM's were always helpful and smiling), I think when we go back to that area, we're more likely to select the BC. The YC did have a more "refined" lobby, which we enjoyed, but I found that I missed some of the things over at the BC that I walked over there for (namely the BC Marketplace, Beaches & Cream, etc.) While walking between these resorts is not a big deal, I think the BC is just a bit more convenient for our needs. We also enjoyed being that much closer to Epcot, and when at the YC, found we entered the resorts at BC and walked to the YC that way, to get out of the heat!
I can also say that my room at the BC was immaculate last year (with the king bed and full balcony I requested, too!

), while our room at the YC, while clean, definitely looked a bit worn (collected dirt around the baseboards, furniture that was once white looking a bit yellow, stains on the carpet, etc.). My parents had connecting rooms to ours, and theirs was in similar shape.
Either way, enjoy your trip!
