That being said, Tres Pelicanos in high season will get what you need at a reasonable price with good service.
Pro dive will be a bit less personal service on the office end, but I have found dive masters to awesome and boat crew very attentive. Guaranteed 4 a day dives and free nitrox. Will store your gear for you, but you rinse it. This is a large boat (cattle boat reference by some) and may not be a best fit for everyone. Need 3 to schedule a night dive
Dressel will get you similar experience to Pro dive. Guaranteed 4 a day, not sure on night dive requirements. Believe free nitrox as well. Again large boats, inflexible scheduled sites etc
Aldora will not get you more dives but yours the benefits of larger steel tanks as a standard option (other ops can get you same tanks or similar as an upcharge) they offer some sites that other ops don't typically visit (especially the large boat fixed schedule ops) this is mostly small boat and small group diving. This may benefit you if you have lower gas consumption and can get significantly increased dive times on fewer dives. If your consumption limits your dives rather than your NDL then this might not be your best fit.
Hope you find what you are looking for. Regardless of who you go with enjoy the great diving that Cozumel has to offer.