Class that requires the most skill

[Asher]

While I don't necessarily consider it skill, these classes are very busy:

Bard - if you like carpal tunnel and not chatting much this is the class for you.
Enchanter - Non stop mezzing, buffing and debuffing and dealing with idiots that break mez.
Monk - puller, hopefully chain puller.

Laziest class is Wizard by far.
Stand, Nuke, Sit. If you can do that you can play a wizard. No buffing or debuffing.
Quad kiting is a bit more involved but on raids or group this class has the easiest job.

Asher