Hmm. Good question!
I have a Normal (950g) and a Miami (350g) who are the biggest sweethearts ever. They both LOVE to be held and are very calm with great demeanors. My amels are also great. I have a couple that I wouldn't trust beginners with, they are too flighty and wild, but I really have to think it is nurture over nature on this one.
Looking forward to other answers!