Hal Jordan would make the most sense. This is a reboot of GL and he's the first human.
Plus we already have an African-American on the cast with Cyborg. No reason to include Stewart for diversity. Diversity is Stewart's best asset. The JS character is quite bland.
Hal has a better mythology to work from, and he's DC's current #1 GL.
My guess is we're getting the first New 52 JL Lineup.