I use a Bringers of Despair Brigade, so i find all of them helpful to some extent.
-Chaos Lord- Chosen of the Warmaster
-Dark Apostle- First Among Traitors if fighting Imperium, Lord of Terror if not.
-Sorcerer- Trusted Warlord
The Sorcerer is the easiest one to shoehorn in. I find the Dark Hereticus pysker table to be really powerful. Warp Time allows me to teleport Terminators in, move them and easily charge. Gift of Chaos is really effective at killing T3 characters, and Prescience can be really powerful when combined with the Dark Apostle's First Among Traitors. I generally don't care for the Dark Apostle, even with the new Prayers. But, for Black Legion, we have lots of 1 CP Strategems that feed in well with the Warlords.