I will add a vote for Panchos...
my wife says the Fish Tacos are the best she has ever eaten. It is really a nice place.
I love Nachi Cocom for a beach day, which is all inclusive, but for a teen, I probably go to Paradise Beach also.
I want to try Mr. Sanchos on my next trip. They just added a second pool and also have a lot of things for families and kids. They also have an all-inclusive rate (about $50 per person) All you can eat, a special reserved beach with chairs and umbrella, ocean kyaks, and of course all you can drink. I plan to go on my next trip to Cozumel, hopefully this fall.