I have stayed at WL, BC, and YC. It's a hard choice - the WL and BC are my favorite resorts. The boat ride from WL to Magic Kingdom is really nice as well as the themeing and great pool. (favorite pool and best theme in WDW).
The Epcot resorts are walking distance to 4 other resorts, MGM, Epcot, Miniature Gold, and Boardwalk which makes it a great choice as well. StormAlong Bay is always a hit with the kids. Either way, try to get a water view room. Boardwalk view at the YC/BC or Lake View at the WL. The view from these rooms has always been the highlight of my trip, especially if you are able to get a full balcony. You will definitely not be dissapointed at either of these resorts! I felt the Beach Club is much more "kid friendly" than the Yacht Club.
Also the rooms at WL tend to be around $100 cheaper a night if money is a factor.