never any place convient, a lot of the nodes in question do not always spawn as rich ... sometimes they are small.
But you asked, so get ready
Winterspring, most of it is overfarmed but the scarry place down south with the demons, most folks do'nt have the balls to go in, my lock mines it silly, usualy 4 nodes back in the area. The blasted lands is the same, check the all elite part"Tainted scar"
EPS has some nodes, as dose sithulius, but most of those are OOZE coverd rich thorium, but thats good, they have better gem drop rates.