Personally I really want the Emperor's children. Just started painting an army of them and noise marines are ghetto.

Am... Personally, i want to see ALL Chaos Legions in game =)

Don´t we already have a couple of threads related to this sort of discussion on the first page already?

But yes, Death Guard.

Alpha Legion, simply because they're a well known legion.

yup, Death Guard

Emperor's Children..

Alpha Legion because they turned into chaos for their reasons (mainly to save humanity!!!).

Black legion.....

No one said Thousand Sons yet, so I will!

I'm strictly Word Bearers myself. From what I can surmise they may not to any of the Individual oriented legions like the World Eaters, Death Guard, etc.

I think if they go with the class types matching the Legion tactics it may be something like:
Night Lords - Raptors
Word Bearers - Healers/Psykers
Iron Warriors - Heavy / Terminators
Black Legion - Tactical