I've been uploading my photos to stock agency's for a year now, mostly as side hobby.
This is my list(in order of preference) of the ones i use, where ive uploaded 100-200 photos:
Adobe Stock
By far the most profitable and generous is Adobe. They offer 40% and if you go exclusive 50% of sales
Shutterstock
Was one of the most difficult to get in(my pics were pretty bad), but they sell a lot.
Gettyimages
aka bully in the yard who only gives you 15% of the sales you make! BUT they sell a lot, i mean shitloads.
Dreamstime
I've heard good things about them, but the time when i joined, it has gotten very quiet. During 6 months i've sold only 9 photos and earned about 7$.
123RF
Despite the awesome domain name, they rarely sell.
Alamy
Alamy uses different angle, with very high prices, they sell very rarely, but when they do, you earn 10$+ per sale!
Pond5
My recent find. Hasn't produced anything positive, but probably mainly because their focus is on videos.
Source: Ungert.photos