Update: Ryan Reynolds got the part.
This week, the race narrowed to Bradley Cooper, Ryan Reynolds and Justin Timberlake. The clock is ticking on the decision as the holding deal the studio had on the actors expired Monday, meaning the three are now free to accept other offers.
My preference would probably be for Ryan Reynolds, but Justin Timberlake might surprise. He's one of the better celebrity hosts they've had for SNL in a few years, so he might have the chops to pull it off - but he's a little skinny for the role.
If you haven't you should read Green Lantern: Rebirth, for someone like myself who only cared about GL as a member of the Justice League and not much more, it made me a fan.