For reasonable sized lizards I certainly like the leachianus. I don't think they have very many morphs, though. Gargoyle geckos caught my attention, as they're around crest size and have some variety to them. Other than that I can't say, I didn't look too far into them since I'm not interested in anything with an adult size smaller than my hand.

Rainbow boas and most corns/kings/milks grow to a pretty manageable adult size? They can get some length on them, but they aren't as thick bodied and bulky as most larger constrictors so they still look smallish. Lots of fun looking corns if you're into those?