I have tried em all, and must say....
Cain Wraiths with a Banshee for the win!
Black Coach is a very evil and nearly impossible thing to pull down, but... takes away your Power Dice and aint great from turn 1.
Varghulf never served me good, they always get taken down quickly...
Blood Knights, have a few things too say here, HELL NICE MODELS! too many know the stats of a Blood Knight in there heads, and for the points and the frenzied speciel rule, sry this unit aint worth it, when every opponent will too easily make us go in circles, a fast cavalry with the opportunity for escape is maybe 90 points. we pay damn near 400 points for a Blood Knight unit and if they dont get to CC we have already lost.
Wraiths, i love them, ethereal, skirmishers, and the Howl. 275 pts for a unit of 5 to make a meat shield in front of your entire army, and also being able to get a few charges in with a movement of 12" and ranged og 8"
Once faced an 1750 pt Dark Elves, he had ofc a hydra, and for the fact whe aint got a unit for such a beast, we dont got the chance of range fire it down before we come in CC, got my unit of there 7 Wraiths in the side of the Hydra through a forrest, (not a charge jsut moved through forrest) and then in shooting fase i took a chance and Howled at the great beast,... it was a 5 and a 6...
this beast got a LD of 6 and my shot deals wound who all is higher then his LD, my shot is called 2D6 + 2 so. i got 7 wounds inflikted and no armour save meant he had to hit 7 dices all over 4+.... he didnt

and down went the feared Hydra

-Nemesis