The only thing we requested at Beach Club was a full balcony, but unfortunately we didn't get one. Having five people in a room makes having a balcony all the more important to us. From what I could see, a minority of rooms at Beach Club have full balconies.
In terms of waterview, we had a much better view at Yacht Club, but that could have merely been the difference between the two specific rooms we stayed in.
In terms of location, they are both great! BC is closer to the Epcot entrance, and YC is closer to the dock for the boats to Epcot and MGM.