The best instructor with the most years technical diving overhead experience above and beyond any of his GUE colleagues, diving both the caves of the Yucatan AND overseas Philippines/Indo-Pacific/Micronesia Wrecks (i.e. Truk Lagoon) is Kelvin Davidson in Tulum:
Who we are » Third Dimension Diving
GUE Instructor resumé | Global Underwater Explorers
Now that's a guy to add to the list - thank you
For once I 100% agree with Kev. Kelvin is the absolute way to go. I've known Kelvin 5 or 6 years now and will continue to do so. I met Kelvin when he did some guided cave dives with my wife and I. My wife and I are very conservative, heavily safety minded, and are not goal oriented divers. We were impressed at how much Kelvin embodies that same philosophy. He is extremely safe, well rounded, and has an ability to teach in a manner that is easy to understand and effective. He's got more dives under his belt than most of his local counterparts. He's also very much an instructor's instructor, meaning he's the guy people in his area go to in order to become instructors or advance their instructing. While he is a GUE instructor and upholds most GUE standards in his regular diving, he is not 100% GUE. He can teach most any course for the major agencies such as IANTD and TDI. The mechanics and adherence to precise skills of the GUE mentality are part of all of his courses no matter the agency your card comes from.
I live 2 hours from florida's cave country, but I travel to mexico to take courses with Kelvin. We're moving into rebreathers in December and Kelvin will be his instructor.
There are many great instructors you'll get recommended. There's also many recommendations you may get for people who actually suck. Kelvin will absolutely make you a safe, competent diver. It's a decision you would not regret.