I definitely preferred Secrets over the Occidental. At the Occidental, I did the "Royal Club" upgrade mainly so I could make dinner reservations at the restaurants every night instead of doing the buffet. There, the upgrade did make a significant difference on the booze quality since the Royal Club restaurant/bar served premium tequilas and other liquors while the other bars mainly pushed generic swill, but the room was the same as all the other rooms in the resort AFAIK, just a little closer to the dock (still a very long walk lugging my heavy camera). My room at Secrets blew away the one I had at the Occidental. Huge, very recently remodeled, and a great ocean and pool view versus the funky little garden area at the Royal Club. Food at Secrets beat out the specialty restaurants at the Occidental, though there were still some inconsistencies.
I've never tried Dive Palancar. People seem happy with them as a resort operator, especially those who like coming back to the resort between dives, but I prefer a small boat op that uses bigger tanks for longer dives and still picks me up right at the dock. Price is a little more for the two-tank day, but when you compute how much I spend per minute of bottom time, it ends up cheaper than dive ops that limit dives to 45 minutes or so.
I also liked the fact that Secrets' restaurants would serve lunch until 3 pm. By the time I'd get back from my two long dives, rinse my camera and myself in the shower, and enjoy my two post-dive beers on the balcony while downloading my photos, it would usually be after 2 pm. At the Occidental, I really had to scramble to make it to the Royal Club restaurant for lunch before 2 pm, but Secrets let me relax and take my time.