Dwayne Johnson
Jensen Ackles
Mads Mikkelsen
or Karl Urban as Hal
Dude ! I've been pushing for Karl Urban as Hal ! Totally with you there.
What about Ackles as Guy Gardner ? He's basically just Dean Winchester with a Power Ring - an arrogant, stubborn, macho hot-head, who's not all that bright but still a hero underneath.
I reckon they should keep Mark Strong as Sinestro, but if not Mads would be a good choice. What about Robert Knepper (from Prison Break) that guy just radiates evil?
But back to the Rock. I agree with the guy who suggests that a Black actor would be the best choice to portray John, and there are so many great actors out there who could carry it off.
Having said that, if the Rock did get the role, it would certainly raise the profile of GL .
He was the highest grossing actor of 2013, with his four films totalling $1.3 billion. Now of course not all of that is solely due to his presence, (as half of that came from FnF 6), but he certainly does have star power to effectively promote the film (whether it's a solo GL film, an ensemble GL film or even a JL film).
I know that the Rock has been mentioned in the same sentence as several Superman villains.
To be honest, the Rock would be a better John Stewart than Doomsday or Darkseid, because Doomsday has zero charm and personality (he's a bit like the Kaiju in Pacific Rim) which is what makes him scary (kind of like the Fury, from Marvel's Captain Britain). Darkseid on the other hand has an enormous personality, and while John Byrne gave Darkseid quite a bit of charm, he also has to project staggering intellect.
Neither of these characters are well suited to the Rock's acting range. John is a tough, straightforward guy with a good heart, well that's how I remember him. IMO that suits the Rock much better than either a monstrous, mindless brute, or an evil genius.
So we'll just have to wait and see how it all plays out. Regardless, the Rock's presence will certainly help whatever film he does become a part of.
Still sorry that it's not going to be Lobo, now that role would suit the Rock perfectly, IMO.