One of the most important things that need to do with Team Comic Book Movies is build up..Avengers did so well because it has build up..but sadly i really don't think Justice League will have many build up movies but i figured it out..here is what i think DC should do
Superman:
Played by Henry Cavil
Build Up Movie:
Man of Steel:
Henry Cavil needs to return for Justice League..Man of Steel will be awesome and he is very likely to be in the Justice League Movie
Batman (John Blake)
Played by Joesph Gordon Levitt
Build up Movie:
Dark Knight Rises
I know this is a very unpopular choice but i have good reasons why i think John Blake will be batman. First JGL has becomes very famous and having a recognizable actor in JL will help it.I know the JGL Reps have denied him being in the JL movie but i still JGL is going to be Batman especially Chris Nolan's reaction to the question (Is JGL going to appear in Justice League.So i think it's a safe bet we will see JGL in Justice League
Arrow
Played by Stephen Amell
Build Up TV Show:
CW'S Arrow:
Personally i think he would be a great character in the Justice League. The Public know about CW's Arrow so he would be instantly recognizable in the Justice League Movie.I also think he could be very different and unique from the rest of the Justice League Movie.
Amazon/Wonder Woman
Played by Shelly Hanning
Build Up TV Show:
CW'S Amazon:
I know the Descpriton of the CW'S Amazon wasn't very good but honestly i feel it could be really well..hell CW'S Arrow was really good and if they do it similar to that..it think it will be really good.As for who should play Wonder Woman..yell i think Shelly Hanning would be a great Job for the role of WW..honestly i think she looks like WW and is a great actress..
To be honest..i wanted to just focus on the Justice League Members..not the villains or Supporting characters. Overral i think Justice League would work if they did this similar to my ideas.