3. Eric Bana (as Guy Gardner)
Guy Gardner was conceived as Hal Jordan's first backup on Earth, and was only passed up for the job by Abin Sur's ring because of his proximity to the alien's crash. Over the decades since, the character has taken some wild turns. Most recently, during the War of the Lanterns, he discovered an unfathomable capacity for rage and violence within him. Armed with the green ring and a red ring of rage, he briefly went out of control and turned his powers on his friends.
Bana would be perfect for this iteration of the Green Lantern primarily because of this subplot. In roles such as Hector in Troy and his lead turn in Munich, Bana has played largely heroic and righteous men who have been consumed by hatred and anger. And he can be good natured or scary as hell depending on what the role demands. This is partially why he was actually a fantastic choice to play Bruce Banner for Ang Lee's Hulk, if only he had gotten a chance to be the Hulk as well.
If Warner Brothers and DC are looking far enough ahead, they would set up the different-colored Lantern Corps within a few movies or possibly as a television project. And Gardner's transformation into a Red Lantern is really the perfect narrative entry point for that. Bana would crush both sides of that coin.