We dive a lot from our own boat - you can guess the brand based on the name I post under -
One good rule of thumb is to look at boats popular in your area - the reason you don't see pontoon boats in your area - or offshore Miami, for that matter - is they are not suitable for the boating at hand - inland lakes, rivers, fresh water.....sure.
If you see the majority of boats in use, I would bet that you will see a ton of center consoles 21 - 31' - if you plan to go out in the gulf, like in so many other things, bigger is better!
I'd also skip anything w/ a cabin - all they do is take up space, and have little practical purpose on a small boat.
PS To Walke121 We had a Contender 31' w/ twin 250 Yamahas for 10 years - loved that boat; so many good times, took it to the Bahamas for years - it got stolen, and we bought the Jupiter 3 years ago - I like it, but would have zero hesitation about going back to Contender - love the 33' - but even used, in this crap market, they want stupid money for them, so its going to be Jupiter for the foreseeable future!