We much prefer Serenity Bay, the adult beach. Quiet, not too crowded, and the lunch buffet is also less crowded.
But...it is definitely away from where the action is (the family beaches). If you like the various live and recorded music and activities (think crab race), the energy of a lot of people around, shopping, water activities such as boating and slides, then the family beach is the place for you. Your lifestyle should guide your choice of beaches, and I can really see the attraction of both depending on what you want your day to be like.