I voted for the Boardwalk, although it was really a toss-up between the Boardwalk and the Beach Club. The reason - location, location, location! We love staying in the Boardwalk/Epcot resort area. You can walk to Epcot and MGM (or take the boats). Plus there's all the entertainment options on the Boardwalk. And I haven't even mentioned all the dining options! Between the Boardwalk, BWI, YC/BC, Swan/Dolphin, and Epcot, there are a huge amount of very nice restaurants within strolling distance.
As far as which resort, we have never stayed at either the Boardwalk or the Beach Club, but we've visited both on every trip so far, and we really like the feel of both of them. For us, the Boardwalk has a very slight edge over the Beach Club, but we'd love to stay at either one. Of course, the YC is right there too, but it doesn't really appeal to us as much when compared to BWI or BC.