I think you will find Cozumel lends itself to a la cart trips; dive op., hotel and where you eat out each confronting you with a mind-boggling array of options.
If you start a new thread describing what you're looking for, people who've dove with give op.s may be able to make recommendations and help narrow it down. The better you explain what you're looking for, the better they can help. Some suggestions:
1.) How important is cheap in a dive op?
2.) How important is ready access to shore diving?
3.) Would big tanks, such as steel 120 cf & long bottom times, be a big draw?
4.) How important are small, fast boats?
5.) Do you want to stay in or near town, and walk to area restaurants, or are you a 'stay on the reservation' type and prefer an A.I. resort down south?
6.) If the resort provided bicycles to ride around, would that matter?
7.) How important is cheap in a hotel? Do you like luxury, or resent paying for more than you need?
8.) I believe Aldora has a boat at a different area they can use if the weather's bad and closes the main harbor, IIRC. Would that be a major selling point?
9.) How important is it to have an op. with a rep. for being especially newbie friendly, vs. putting divers on more experiences boats where they're not 'held back' by the 'least common denominator' (I am not trying to be ugly about that)?
Some threads to get you started on some options:
Blue Angle Resort and Dive Shop (a recent trip report).
Aldora Divers vs. Scuba Club Cozumel.
Scuba Board did an Invasion trip to Cozumel and I believe used Hotel Cozumel and the in-house dive op. Be mindful that op. could handle their large group; many op.s wouldn't have been able to. I've noticed Hotel Cozumel is a fairly popular hotel choice, though divers may use a range of outside op.s. Another poster has indicated if you book a cheap package with Hotel Cozumel that includes diving with the in-house op., you may be stuck with the slower boats, so be aware.
Richard.