Risen...lots and lots of Risen...
The Cursed are without a doubt one of my favorite Devout units. Being Undead, they are immune to Morale, and Panic. Add the Unholy Champion to the army, with the Avatar of War Standard, and they're just plain nasty. A Warped Lord with Dark One's Fury is also wicked, and makes their Battle Axes that much meaner.
Any of the other big fuglies of the Devout are also great centerpieces for an army, besides the Soul Flayer. An Abyss Crawler is slightly fewer points, and with 6 Wounds, Tunnel, and Trample, his large base can trample entire Warbands at a time, with space left over....yum yum....