Hey Mark!
At the time of your posting you were working at Aqua World, it would be interesting to know your opinion now that they fire you!
Look, I know this post is from long time ago, but here is an updated if it is any good.
Manta divers - terrible, horrible, mean and greedy, plus take care of your YOUNG daugthers, some perverts around there!!!!
Suba cancun - I can`t really mention about them, as I have only HEAR, not expirienced personally, but the opinions were not so good.
AquaWorld! ... please ... they are like a fast food restaurant, and carefull with your own gear, as many of the people working there are knwon to be tiefth ...
Do I know good instructors? Yes, many have left cancun, but still some very good decent people there that will not rip you off, I know of Alex in wich I did personally did some training with him ... I`m sure their are more, but this is the one I still keep in touch.
https://login.passport.com/ppsecure/md5auth.srf?lc=3082
Hope this helps someone ...