I've used Snazaroo before, but they're just too much work. I've just gotten into Mehron, and they are fantastic paints! A little more for the buck, but WELL worth it. Also, have heard fantastic things about Wolfe Bros. , but just haven't purchased any from them yet--they're next on my list!
I know that they really have staying power and do not come off in heat. Excellent product. GREAT website. Check it out. Gigi it correct about the acrylics. Be careful...not FDA approved means make sure you have a disclaimer stating that you are not responsible for allergic reactions. Better safe than sorry.