Poser is the best one for figure creation. It comes with quite a few models that can be modified in many ways, and you can buy additional characters, clothes, props, etc. for it.
Motion Builder is strictly an animation package, and it’s better at that than Poser.
Poser is probably the more intuitive program, although I wouldn’t say that either is particularly intuitive to be honest. One thing Poser has going for it is a large user base, so it should be easier to get tutorials and help.
I’m not familiar with Figure Art — sorry.