Mashing taunt is never a viable method of holding aggro in this game. Not at level 10, not at level 60. Once in awhile it'll flip a target back to the tank, but even then it fails more often than not and it does nothing to hold aggro.

Danth

It fails a lot, because it will be such a low level skill.

SK will be the best aggro-holder. Disease Cloud is immensely high aggro and, when higher amounts of threat area required, a Darkness is essentially guaranteed aggro. SK also gets Feign Death, remember, and thusly can act as a semi-reliable puller. Additional utility such as Invis, the ability to Slam (Troll/Ogre) to interrupt casters. Fears and Snares which allow them to solo in outdoor zones when your premade isnt around. Remember that a Troll or Ogre SK is gonna have a rather impressive 60% experience penalty!

Pally has Flash of Light which is above-average aggro but can be risky (mobs will run if the Paladin moves outside of their melee range). This would change at level 30 when the Paladin gets his first of the Stun line of spells. These are incredibly high aggro but can drain the Paladin's mana quickly when spammed. Additional utility there would be the obvious ability to heal party members. Lay on Hands to SAVE party members. Lulls and roots for pulling and finally the ability for Rez in the late-game.