I'm not a chameleon keeper, but a friend pointed me to this thread. I've been keeping a group of Leucomelas for a while, and they're great! Once you've built the viv, they're very low maintenance, compared to chams. The biggest thing for me is that in a properly designed viv, you don't have to clean up their poop.

(I get enough of that with my cats...)
If you're just getting started with darts, I have to strongly recommend leucs as a first choice. They're tolerant of higher temps, quite bold, and do well in groups. They also tend to be bold, so you'll be more likely to see them active in the tank. Tinctorious are notoriously aggresive if not in a sexed pair, and are semi-hard to sex. Auratus tend to be on the shy side, so you may not see them as often.
The only potential downside to leucs is their call. They have a surprisingly loud, canary-like mating call. Depending on the location of their tank, this could be an issue for you.
In any case, they're super cool, and I strongly encourage you to seek them out at shows. Pics on the web simply don't do them justice.
-Allan.