I don't think you can legitimately say its going to be Green. First, we don't know who his quarterback is going to be. Second, he is still competing with two other diva's at the WR position.
If you're judging greatest impact by Wins/losses, its hard to say who will have that impact. But IMO Peterson gives the Arizona defense the chance to lock down his side of the field and focus on the other. I think he will do the most for his team in terms of what they are able to do on one side of the ball, but I'm not sure about w/l. Von Miller will be tearing Shat up too, no doubt about that.
Also, as Jaytrain said, Jones has a great chance in being that possession receiver along with some big plays in the Falcons offense. I wouldn't be surprised at all to see him average 5 or 6 catches per game next season.