If you want something that is out often and is not easy to kill I would recommend B. Smithi, they are pretty, out a good amount of time, are fairly hard to kill, and they get fairly large. They don't have a bad temperament, although they can fling hairs. Also getting an adult shouldn't be too expensive. B. Vagans is another good option, but I wouldn't say a sun tiger( P. irminia) is a good first T... their bite is pretty bad, and they are skittish and defensive.
Slings can be hard, as with most things, the younger you buy them the more likely they are to die. I tend to say that if it's your first T an adult is probably the best way to go.