calla bassa is actually one of the nicest beaches imo. Its busy sure, but the water is crystal clear, sandy bottom and no "stuff" like seawheed or ugly fish in the water. I´ve been to quite manym but you schould also check out cala Moli for the lovely es vedra rocks, Benirras (altho I didnt get the hype honestly), calla vadella and salinas. Havent been to salinas myself but alledgly thats the "place to be" where you have ther jockey club and sa trinxa.
if you want a beach like any other beach in the meditteranian go to playa d´en bossa. big, long beach that looks like so many other beaches anywhere basically.