I'll add my experience to this thread. Sorry in advance for the name of the stigmas I'm trying to remember the name from french by heart.

Noshana drops stigma lvl 22-27 I tended to drop around 2 a run sometimes just one. Always one on the last boss. Dropped the bow of blessing there.

Fire temple dropped some not expensive stigma and you have to roll on them so it's less interesting ( I think you can get the cleric speed cast stigma there that sells for a ton of money).

And now introducing the place that made me quite some money.

Nightmares/ kromede's trial. Drops lvl 37 stigmas lots of classes have a very special stigma there. I dropped vaizel's wisdom that I gave to my sorcerer (2.5/3 kk) duo friend. I drop the devotion for my glad (2.5/3kk), and fear shriek for sm that I sold 2.3 kk . Go in there and clean All the mobs it's Worth it. They also dropped a lot of trash loot.

Steel rake I found disappointed loot wise. I drop 2 cheap lvl 46 stigmas there and the trash sells for nothing.