[Endorra]

From 12 to 45 or so, option #1 works best. Lower level mobs just don't have the depth of HP to last very many fights.

After 45, due to the scaling of mob HP and damage, #2 becomes more competitive. However it remains risky because having a hasted, dual wielding beast break charm and come straight at you is bad news bears. The better strategy is to charm something, haste and weapon it, then intentionally break charm to keep it rooted/blurred and charm other targets to send against the "super mob." When they get low, break their charm and kill them, then blur the super mob and repeat. This strategy is what I learned to call "reverse charming."

After 51 (54?) when you have access to the best mana regen, #2 or the method described by Emmin above (using a charmed mob to gather several others, then the rooted pack kills itself one at a time) can become superior. This is, again, due to the nature of NPC dps/health scaling. When you're 55+ having 1 charmed mob fight 1 enemy mob down to 10% takes waaaaaay longer per fight than it did at level 30.