The Catalina is the best liveaboard of the three you listed, though you'll need to add some canvas (a dodger at the least). I don't completely agree with the swim step comment. I'd love to have one on my boat. True, the water is colder up here, but a step makes getting in and out of the dink easier. Especially if you have a dog or children. And there are a few places to swim from your boat where you don't need a wet suit.
