Drak'Tharon keep is my all time fav HC, its simply still fun to run it, i would say "easiest" also with Gundrak and UK,

when i began boxing WotLK HC when still in blue i200 with the odd epic i200 my daily run always consisted of UK Drak Gun, i did the other for specifik items like UP for tank sword or Nexxus for healing mace and so on, but still when i do random and get Drak i feel good in the soul.