Shutterstock: a good place to start because they give good support materials and useful technical feedback. On You Tube many contributors make most of their income from Shutterstock because of volume of sales
iStock Photo (part of Getty Images): photos, illustrations, video. Take 45% commission.
Adobe Stock (took over Fotofolia)
Smugmug Pro can make good money. Make own website and pricing.
Foap: amateur phone Ap where you can sell direct from your phone
Clashot: sell photos through an Ap you set your own price 50-80$