Mexican caves are utterly spectacular. They were vadose limestone caves that became flooded after the most recent glaciation ended. Thus, most are heavily decorated with calcareous speleothems. Typically the caves are long and shallow with low flow. You can easily spend 2 to 2-1/2 hours swimming 7,000 feet and never get deeper than 40 feet and never get into deco. Of course, there are deep caves too. Diving the sump side of centoes takes some gas planning but it's possible. The passageways tend to be complex and the cave lines have a lot of complex intersections. Deco diving is not common unless you are doing extended-range or deep exploration. The cenote water can be fresh, but close to the coast there is often a mix of salt/fresh water with a bothersome halocline. Some caves trend along the halocline so unless you're in the lead you never get to see anything except a big blur.
Florida caves were always phreatic, so they're rather dull, just tubes in limestone. Many think the Florida caves are beautiful, but I've been in several hundred caves and would not agree. Florida caves tend to be quite a bit deeper with high flow, so they are significantly more challenging than Mexican caves. Deco is often necessary unless you're are doing only cursory penentration. Almost all caves in Florida are freshwater. I don't think I'd ever want to dive the sump side of a Florida cave unless the conditions were perfect.
