BRD (all 22 bosses)/ LBRS/UBRS Stratholme and Scholomance.
These were among the last instances you ran pre raiding.
You run heroics pre raiding.
With a return to the old end game crafting mats of Elementium (used to be the name of the stuff that dropped in BLackwing Lair(now called enchanted Elementium)) and Obsidium (used to be farming from killing mobs in Ahn'Qiraj 40) A return to the old end dungeons would be nice.
I never really ran SFK or Dead mines much while leveling. But I did run a heck of a lot of BRD, Blackrock Spire, Stratholme and Scholomance. Onyxia attunement, UBRS key (when the gemstones werent a 100% drop off all 3 bosses)