All very different sites - La Baie is near to town, walking distance to all the beaches and activites of Cavalaire (which out of season can be quite quiet), Le Cros de Mouton - fantastic situation, overlooking the bay with lovely views, drive into town, Le Bon Porteau, adjacent to a lovely cove, but drive into town, Selection Camping - great situation, adjacent to the beach, but the quieter end between La Croix Valmer and Cavalaire.
We stayed at Camping de la Baie years ago. We have friends with a house in La Croix Valmer who we visit regularly, so these days I wouldn't know how to choose between. In September, perhaps La Baie, or Selection Camping, because you don't have the drive into town to shop!!
A fantastic area - do visit the Gigaro beach at La Croix Valmer, or Chez Camille near Cap Camarat, for one of the most lovely beaches on that coast.