2. Green Arrow
There are many people that think just because Oliver Queen has his own TV show and Hawkeye is in the Avengers, it means that the Green Arrow won’t get a chance to join the league. Ignoring Oliver Queen in the DCEU would be a mistake, though. Adding Green Lantern someday is a given and the friendship shared between the two of them is a thing of legends. It may take until Jeremy Renner retires from the Avengers films and Arrow ends, but someday they should bring Oliver Queen into the big leagues.
His personality is very different from Hawkeye and his style sets him apart from the other league members. Oliver often rejects the league’s tactics and actions because he is always looking out for the little guy. He doesn’t necessarily see the need for a team and has even refused league membership a couple of times. When everyone in the league has the powers of a god, they can sometimes overreach. One day when the league pushes things too far, I could see Green Arrow leading another group of heroes against them to show them they aren’t always right.