The first site I joined with is SMS.ac but I think it is still alive just changed the name to FanBox. The site paid its members but turned to be a scam site.
Then I joined Friendster, mySpace, Hi5, Tagged, etc. but they were not paying. I lost interest joining social sites since Friendster closed.
Bubblews came paying its users so I tried. Then PostAnyArticle and PersonaPaper. I didn't reach payout at PersonaPaper before the site stopped paying but Bubblews and PostAnyArticle paid me many times before they disappeared. 😊
Today, my favorite paying sites are myLot and bitLanders because I can comment as much as I want. And my favorite non paying site is Twitter because there's a lot of good articles tweeted everyday.
Steemit is already mobile friendly (I prefer phone browsers than apps) but not user friendly.