If you are going to be doing a lot of towing or towing long distances, it might be better to look for something a bit smaller, like around the 19' range. You won't be able to overnight as many people, but the lighter weight and easier set-up reduces the hassle considerably and will let you go places that the larger boats can't (which is a
GOOD thing in the Keys).
Having said that.. when we were looking at downsizing from our former H27, I looked at tons of boats in the 25' and smaller range; specifically because I wanted to be able to trailer it and not be slip bound like our H27 was. Of the three you mention:
H22: In my opinion, the H22 has one of the best cockpit layouts of any in this range, but I'm not that crazy about the keel locker obstructing the cabin space or it's somewhat constricted (to me) forward berth. With it's keel retracted, it can get into just less than 2 feet of water, but can lower to 5 feet when out in open water. Weighs in at 2600 pounds and is fairly easy to launch/retrieve.
H23: A bit bigger, gets rid of the obstructive keel locker (which allows the cabin to be converted to a queen sized berth), and actually weighs a couple hundred pounds less than the H22. Uses a sliding galley instead of the fixed one in the H22, which frees up cabin floor space, but effectively eats half of the port side berth. It's wing keel version has a 2'3" draft, but some early '85 models had a wing/swing keel that takes that down to just 2 feet with the keel up (4"11" with the keel down). Wing keel version weighs in at 2450 pounds, and wing/swing keel version is 2300 pounds.
H25: An older (Cherubini) design which began production in 1972 and I believe was the last Cherubini designed Hunter to be sold (ending production in 1983?). Very robust design and Cherubini's in general have a large group of fans for that reason. However, it weighs in at close to 4000 pounds and has a fixed keel that needs just a hair under 4 feet of water, making it harder to launch/retrieve as well as tow. We kept our H27 in Key Largo, and it's 4'3" keel was a constant problem on the bayside of the Keys (where it can get real shallow real quick), so the H25 might have some of the same problems down there as well.
Cheers,
Brad
PS: Nissan may say you can tow 6000 pounds, but it sure won't be fun, might not be real safe, and you wouldn't want to do it for any kind of long distances.. Chevy says I can tow over 10,000 pounds in my Silverado, but there is no way I would consider coming anywhere close to that kind of load unless I was just going down the block

I've found that trying to tow anything over about 3/4 of what my vehicle weighs starts to get a little froggy. ymmv.
PSS: I forgot about the newer (2005+???) H25's.. so if that is the one you were looking at instead, disregard my H25 comments above