Mid teens to 20s: Beren’s Peril in Silverpine Forest.
Early 30s: Shimmering Flats. Iron/Gold around the edges and in the basilisk pit.
Late 30s, Alterac Mountains Yet is.
Lethlor Revine in the Badlands and Crystalvein Mine in STV for early 40s.
For 60, my favorite grind spot is Terror Wing Path in Burning Steppes. The dragonkin drop coin along with lots of trash greens and greys. I’ve even gotten two epics.