My understanding is that this purely depends on ur class. I am not experienced with wiz or demonhunter so not gonna say anything on them but for a thanking barb or monk, definitely enchantress for extra armor cc etc. For a witch doctor Templar with main goal of jusst loading him with vitality. My wd uses z dogs and gargantuan so another person on the field soaking up dmg is the way to go Imo.
Scoundrel with Buriza w/ high chance to freeze (close to 15%), high pierce (75%+), Star of Azkaranth with close to 5.1% chance to freeze, two rings with 9% attack speed. Pretty easy to kill anything (and thus not die) when the whole screen is frozen.
I currently uses the Enchantress but I'm thinking that the frozen Scoundrel would be nice for the Alkaizer run when a lot of the time there is 5-6-7 mob on you. The more mobs are frozen the happier my barb will be.
Would be great if you specified which class you play as well.