Rares was another thing MoP got right imo. They had difference mechanics depending on their race and were an actual challenge to kill at the start of the expac. Skymirror and compass are still two of the best toys in game, and those mobs were camped for the entire expansion and some time into WoD.
Could make some good money killing the zandalari rares too.
Imo Legion handled rares best. WQ up? They’re there. It made farming the mount so much more tolerable since I could just move my alt army to Argus and knock out all the important rares without having to wait an hour for the spawn like Rustfeather or god forbid, Soundless.