Brandon Routh as Kal-El/Clark Kent/Superman-He was perfect in "Superman Returns", no need to change him.
Sam Witwer as Bruce Wayne/Batman-He can play dark, troubled characters, which is also great for villains, and he looks just like the comic version.
Victoria Hill as Diana/Wonder woman-She almost definitely has the part and in my opinion, looks exactly like various versions of WW, including the JL cartoon and current comic books. She can do a perfect American accent too.
Geoff Stults as Hal Jordan/Green Lantern-DCUniverse suggested this pick and it is a great one. He looks exactly like Hal and sounds like what I picture Hal's voice to be.
Scott Porter as Wally West/The Flash-He has the part and I'm not complaining. He looks just like JL cartoon/comic Wally and sounds like Michael Rosenbaum. He can play comedic and is a great actor.
Kevin McKidd as Orin/Arthur Curry/Aquaman-I changed my pick because McKidd is so much better for Aquaman than Armie Hammer.
Dwayne Johnson OR CGI/voice of Carl Lumbly as J'Onn J'Onzz/.John Jones/Martian Manhunter-Johnson wants to play the role and looks exactly like him. Lumbly's iconic voice should be used for the movie version too.
That's all for now, maybe another one coming later...
Guidelines to making a perfect fan fiction article.