That really depends on the story they're trying to tell in this film, and where this DCLAU is headed.
If Lex is in it, but he's not a villain yet, then I'd like to see him in a manner that we glimpsed in Superman: Earth One II, and was explored in the early years of Smallville. A man who is genuinely trying to help, and is not a bad man, he just has bad things happen to him. This, is what I would like to see, then if a solo Superman trilogy emerges, he acts like Azzarellos's Luthor in Superman 2 and then like Grant Morrison's Luthor in Superman 3.
As for Superman, let's just say, I'm glad Man of Steel is out of the way. I'd love for him to be written closer to his Golden Age roots, and how Mark Waid and Grant Morrison write a young Superman (Birthright/Action Comics v2 1-18). He's brash, a little arrogant, even a little bit rough with criminals, but he's always trying to help the people at the bottom, and as both Superman and Clark Kent, he tries to depose the people who stand on their shoulders.
Now, there's not much that can be done for Batman right now that would be fresh, The Dark Knight Trilogy dealt with the three biggest areas of Batman: his beginning, his greatest foe and his ending.
However, if the rumours we are hearing of Batman having parted ways with Grayson recently are true, then it's gonna have to be some of the crap from the late 80's- early 00's, however, I'd rather good stories that tackle a similar period of his life like The Dark Knight Returns or Kingdom Come. Which would be okay for one film, but if he is to receive his own solo series after this, I'd rather this film be the catalyst for him becoming more like the Grant Morrison Batman.
