It's the luck of the draw. My mostkindest and gentle cyclura has been a male rhino. My most vicious and nastiest has been a male rhino. He was so vicious towards me, he would beat his nose against the outside wire just to get to me. He almost killed his mate. I had to feed him at night when he was sleeping. I opened the cage once, and he "full on" sprinted chasing me around the yard until I grabbed a rake to protect myself. I pinned him down, and grabbed him behind the neck and held him for five minutes. I tossed him away from me, and he came right back at me. Funny thing is, he was only this way towards me! He ignored everyone else. Needless to say, it got old and I had to sell him.
This male I have now has an awsome disposition. I also bought a baby pair from KWE a few months ago, and these guys seem pretty nice. They don't fight and get along in the same cage.
My lewisii are super gentle also. My cubans are a little skitzo although I have heard from most that they are the tamest species.
This probably hasn't helped you at all, so I would get whatever you think looks the best.