Say you pick the shaman, and you are kiting. So you add the Necro, and that's a second pet, plus more dots, and fear to go with the root rot of the shaman. You could add an enchanter for Clarity and Mez; charm once you get comfortable with the setup.
If you go shaman necro for kiting and root rot... No need to add chanter for clarity... Necro won't even want it because necro Mana regen is better. And shammy can do well enough with canni... Would be better off going another dps class like mage or wizard.. I would go mage personally... Oh wait I did.... I run shammy/necro/mage and I absolutely love it. And the only thing that slows me down is my kids at home...
But if you are choosing from your current classes. I would say monk/shammy for sure as that duo cam go far into game on its own... And add necro or wizard.
-ability to fear kite
-snare(never over look the importance of snare)
-basically unlimited Mana
-insane dmg to undead.
-over all more utility then wizard.
-insane dmg once monk has aggro.
- and that's it... Wizards are boring
Only downside of a necro would be you would have to make sure all are iksar... Because really people would look at you wierd if you weren't.