Well in order of Priority I would like to see:
(1) Inquisition= All 3 Ordos with Sisters, Grey Knights & Deathwatch options plus inducted Guard & SMs.
(2) Chaos Legions= for all the guys who want the impure flavour of the origional Traitor Legions.
(3) Dark Eldar= who have waited & waited for soooo long!
(4) Adeptus Mechanicus= Awesome possabilities of very different models/rules/ vehicles.