I've stayed at both resorts, and I feel that BoardWalk actually has more rooms with peaceful views than the Beach Club. I think the Beach Club is a smaller resort, with about a 50/50 chance of getting highway view. The Highway doesn't bother me, because I've grown up with traffic noise, living on a busy highway. But, for some, even with the sliding glass door closed, they can hear that highway noise.
I love some of the areas around Beach Club, for lounging, but BoardWalk has those too, and BoardWalk has those wonderful rocking chairs on the Verandah. I believe Beach Club has them too, but not as big a sitting area.
The noise at the BoardWalk, if you have a BoardWalk view, is definitely there, but when I close my sliding glass doors, I do not hear anything.
Both resorts are lovely and have pluses and minuses! Actually, I'd say, you can't lose choosing either one of them. I believe Beach Club is actually a closer walk to EPCOT, and That I liked a lot! But, BW has more eating options. And, there is a nice peaceful set of rooms that overlook the water way and MGM Studios, I believe they are standard rooms too, and cost less points. And, I've found the standard rooms overlooking the Valet area to be a great place to stay. You get a great room for a lot less points.