He seems to be #2 at this point, although Wes O'Neill is still ahead of him on some lists. And AJ Thelan certainly seems to be moving up, and could easily surpass Green. As could Smid or Meszaros in terms of any particular team's preferences. Especially given Green has been hurt of late (it seems), and his team will not make the playoffs. He could go anywhere from top 10 to late in the first round.
In terms of comparisons, that's always tough, but given he is good at everything and has tremendous skating ability, with his size (not small, just not big) being his biggest downside, a comparison to Desjardins might give you some idea (maybe a tad more physical). Actually, Dany Markov might be a good comparison.
The other issue seemingly working against him is he is older than pretty much every other defensive prospect (save Lepisto), so he is expected to be a little further ahead in his development and sometime hasn't been given enough credit because of this. But most scouts sound more sold on him now than 3 or 4 months ago. He had a great CHL prospects game.