Mote of Air

Highest drop rate is from the Storming Wind-Rippers on the elementals plateau in Nagrand. You need a flying mount to get there.

Since Motes have a use function, you can drag them to your Action Bar to easily track how many you got while farming.

While the highest drop rate for Motes is still on the Elemental Plateau, the 2.0.7 patch nerfed the respawn rate on these mobs. Pre-patch there used to be at least one elemental active at all times. Each time you killed one, another one spawned at any of the 10'ish spawn locations. You could easily have 2 or 3 people farming there at once, and not have much downtime. Post-patch, the last mob killed doesn't auto-spawn a new one. This results in substantial downtime with multiple players camping the area. One player alone can farm almost continuously, but 2 or 3 players make grinding here very difficult and slow. This should drive up demand for Primals, and also have the added effect of more PVP to control who gets to farm, but will make farming more difficult.

Where before I could farm 4 primals and hour, while one or two other people were also camping the same elementals, I can now get about 3 primals if I'm all alone, and half that if there's one other person.

It's starting to feel like farming elemental fire at the Circle of West binding all over again.