It seems like the best new chaos armies are those that mix their gods as heretical as that might be.
If you want to do a one god list, all nurgle death guard seem to me like the best one guard list.
All T-sons while not as terrible than before are only mediocre. All slaanesh is too weak other than the lashers, and all khorne has no fire support.
All nurgle lets you load up on plasmaguns and basically never worry about overheating while you slowly move toward the enemy and out firefight them.
Matt did this succesfully even against necrons.
