I'd say the senegal is pretty good. Alotta people say that veileds are but, they require more humidity and heat witch makes it hard to keep higher humidity levels. They will also tell you a panther but agian, they are hard to keep and they are expensive. If you can provide the levels needed for a panther or veiled then go ahead. I found senegals are cheap and have less to care for. You should just ask more questions and see what you get.
From the few chameleon species I have kept, I would have to say the Veiled chameleon is more forgiving. However, keeping a chameleon is not easy. They are expensive and require daily care and monitoring.
A good place to do some research is the Chameleon News website. There are good articles on chameleon husbandry and the costs of keeping a chameleon.
I would agree with Brad that Veiled chameleons make the best beginners chameleon. I would always recommend a male sub adult Veiled. Having said that, no chameleon species is easy to keep and Veiled chameleons are prone to MBD. Females live a much shorter life than males and can experience problems such as egg binding. Laying eggs seriously threatens their lifespan too.
Hi...welcome to the forums. Although I do not have as much experience with chams as most of the other members here...I would have to agree with what the others have said here and from what I have read...that the veiled is probably the easiest of the chams to keep. I have had a M/F pair for over a year and I must say they are pretty tolerant (of course that does not mean to slack on husbandry requirements). I just recently acquired a panther pair also and so I really am just beginning to learn about them...(they are definitely much more colorful than veileds but a lot more expensive...an average 6-8 wk veiled should only be about $30 U.S. dollars...be careful about ads for veiled color morphs because they really don't exist (unless someone here has a different opinion about this))...but they appear to have much higher humidity and water requirements than my veileds. As far as the female veileds go (I need to post a thread later about this because I have some questions) they are prolific breeders and can/will lay infertile eggs even if not bred (my understanding is that panthers also do this). I don't know much about the difference in energy requirements to make/lay infertile eggs vs. fertile eggs and if the cycles between the two are different in length (e.g. how much longer a female who has not been bred but still lays cycles of infertile eggs tends to live vs. a female who is actively bred.). Overall, I would recommend starting with a male veiled and maybe try to find one at a local reptile show if available (if not then ordering one online).