Decent is definitely a player. Their ICO was pretty huge. Content creators don't draw off a pool though, that's the one thing I notice. But that may have the benefit of making sure people really believe in what they upvote.
Not sure about Adbuzz and Coinsyde. I can't find much about them, even on their respective pages. Respectonomy I'm strait up skeptical about. Their dev page looks sketchy as hell. And their whitepaper is of the wordy, ambiguous variety.