What kind of lizard should I get?

I have 55 gal. I have had leopard geckos and found them extremely boring. I absolutely adore my friends chameleon but I want something medium sized preferably without needing constant care. I don't like the dragons very much and I'm not much of a snake person. So what kind of lizard should I get, that is medium sized, not aggressive, but has personality? I understand all lizards very by individuals bit by bit, but I'm talking about generalizations of the breed.