Artstation is surely not for everyone!
I'd say tumblr too. It becomes quite pouplar, and can have personalized themes too. I really liked this feature, it can make you have your own little art blog/portfolio/whatever.
I know there are some facebook groups people use for interaction between people with their works. I tried it for some times, but the groups I went in were bitter and jealous about the others. They praised only the one who were popular, always criticizing the others. Maybe I was just in bad groups.