Hello Mike,
It is great that you asked this, great for people to know a little more about it since I have seen you post and even recommend so much about the area so it would be great for you to visit and provide an opinion
Cancun is underrated, the fact is that Cozumel is World Class for a certain type of dive and since that type of dive is not in Cancun divers tend to say Cancun is not as a great as Cozumel, this information has changed from "Cancun is not as great as Cozumel" to " Cancun is not good "
In 20 years diving in the area and meeting many divers I can as well mention that at times divers get used to diving at their local dive club or want exactly the same thing as when they dove in x dive center and some times wanting to have exactly what they had in terms of structure, prices, visibility, weather etc.
Another fact is everyone has expectations,and then an opinion, unfortunately different factors like weather can create a world of difference on the same exact dive with or without current combined with Thermocline that brings bad visibility (here bad visibility is 35ft)
Other factors can be so many that when are combined and as well depending on the diver, the result a dive or in fact how the dive was perceived even the same dive for divers on the same group.
Cozumel´s "Theme" dive is "Wall Diving". The amazing gigantic coral formations combined with depth and magnificent visibility 200ft. Wall dives are done at the "edge" of the wall where this coral develops. There are different wall dives, some with a nice drift that some times changes to higher currents, this has generated opinions about this dives to be "dangerous"
Cancun does not provide "wall dives" but it is part of the same coral reef system the Mesoamerican Barrier Reef System.
Cancun provides "theme dives" as is the Wreck dive deep dive 75ft.
Coral reef are located as barriers of coral reefs, this are part of the same barrier with interconnections between La Cherna to Herradura and from there Punta Negra, Grampin, Tunel. Or outer barriers such as Aristos / Iglesia system. San Toribio / No name / Cuevas de afuera.
All these are fantastic coral reefs, and after many dives I can say sometimes it is just fantastic, and see all kinds of everything and the next day it was not there and/or weather changed. (waves, winds, currents)
Cancun provides a great place to begin diving. Coral Reefs between 27 to 33ft. Chitales where we see turtles, Manchones long coral reef formations. Manchones Chico. Bandera is a fantastic reef with lots of all kinds of life down there at times a harder to perform dive due to currents.
Under water museum, many divers like it and come back to see the development or changes, other divers do not like it, it is again a matter of taste or opinion.
I have seen written opinions of great dives in Cancun and Cozumel and as well have seen the same for Cozumel many great dives comments as well as notsuchagoodtime comments as you will probably have here on this thread.
To me "anywhere" is a great place to dive, and I am aware that "anywhere in the world" diving may be affected by weather.
Here is a compilation of videos of Cancun dives:
Miguel Cachoa - YouTube
I hope this info helps
Happy diving!
