Jeff Green, I believe, is a superior ball player, and can score on just about anybody. Glen Davis isn't horrible by any means, he's very good. I just don't think he's better than Green.
If Green gets his confidence up, and is in a position where he has to be the go to guy on any given night, he can be as dangerous as a Paul Pierce or a Kevin Garnett, or any serious scorer in this league. I think he has showcased this fact pretty clearly throughout his career so far.
He has even showcased this much very clearly in his best games for the Celtics, where he just stays as aggressive as possible, and actually tries to look for his shot.