Yacht Club all the way!!!
One thing I did notice that would make a difference is the bus service. I recall on 2 different occasions that the bus filled up at the Yacht Club or Beach Club and then never went to the BoardWalk. I'm sure they called a bus directly to BW but still, better chances of seats from the YC.
The Yacht Club, IMO, seems more romantic. You can always enjoy the BW on a walk around the lake. The view of the BW is much prettier across the lake from the YC than vice versa (nighttime, speaking).
Remember, if you choose the YC, request on your reservation: garden view/lake side.
~DawnMaree