If you check the sticky at the top of T/A's Cozumel forum dated 2008 you will see me listed as a DE. I no longer serve as one for a lot of reasons including exactly what you've seen looking at reviews. Bad reviews seldom get published & if they do they get contested & removed. TA is not very fair in how they give out ratings nor will they explain exactly how they do it. Over the years Secrets has changed names several times & with each name change there were lots of great reviews posted within a few hours of the name change, and reviews for it under the old name were instantly gone. Explain things like that in a way I understand & maybe I'll rethink my position about it being fair & truthful all the time.
As for which dive shops are the best, that's easy. Follow along here, read back many pages, see who the majority of us use (we use several amongst the active members) & keep in mind just like there isn't one "Best" meal everyone can order on the island there isn't one best dive op, nor a way to set a standard by which to judge them all.