As a user and contributor of stock, I have my favorites. If I had to pick only one for both, it would be
Dreamstime.
As a seller, I like that they are one of the fairest sites for microstock contributing artists. I also really like the tiered system they have created for our content. I think it allows for a more even playing field. You can have 2 or 2000 images, but both portfolios and members get relatively the same treatment. I guess as you get more and more files, you may start to think it's not so fair. Many sites tier systems are based on user downloads which separates the members into group levels.
As a buyer, they have fair prices and a decent website with the features I use. I have used other sites and have my favorites for this or that; but if I had to pick only one it would be
Dreamstime.
Who do you like the most and why?