Zack Snyder really tried to challenge the public perception of Superman. He dived into some of the more mature themes and ideas that post 80's comics often dealt with. I was thinking which ones led us to his Superman and the DCEU as it is for better or worse.
1. John Byrne's Man of Steel: Clark first and Superman second, it may have always been that way originally but don't come looking for any Superboy in Snyder's Universe.
2. Miracle Man by Alan Moore: There are shots of General Zod that absolutely remind me of Kid Miracle Man. Add that and the devastation of Metropolis, Super people on Earth are seismic events and Snyder did it on screen almost as horrifically as Moore and others did on page.
3. The Dark Knight Returns: SO much fun to see on screen, I know it hurts as a Superman fan, but what can you do. (I kind of think Barbatos might be working with DCEU execs.)
4. Alex Ross's Justice League/Kingdom Come: I have been reading his JUSTICE series and there is so much Ross's Superman in Cavill.
In my dreams the Justice League movies would be 1. White Martians 2. Crime Syndicate/Legion of Doom 3. New Gods 4. Kingdom Come. I also think the detached and distant Superman of Kingdom Come would be consistent with the wandering Clark of Man of Steel.
(Honorable Mention: Howard Porter's Justice League, when I look at Momoa's Aquaman, he just takes me back to Rock of Ages)
I definitely don't think there is a dearth of source material for the DCEU. I wonder if general audiences just weren't ready for such a new Superman.
I hope we see a Justice League again soon. I think it's inevitable it will gain in appreciation once it's screen at home. I personally am willing to forgive ALOT to see more Justice League on screen. Oh well, still got the comics!
I'm sure I missed some comics but I figure since Zack is my generation he would have about the same reading list!