If you loved Justice League: Gods and Monsters, try Justice League: Crisis on Two Earths
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Justice League: Gods and Monsters
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Justice League: Crisis on Two Earths
What they share
Both films are directed by Sam Liu, and they sit in Action / Adventure / Animation / Fantasy / Science Fiction territory. If that's the register that drew you to Justice League: Gods and Monsters, the second film will land in a comparable space — through a different lens.
What Justice League: Crisis on Two Earths is
You're a Justice League member, answering an appeal from a parallel Lex Luthor. The Crime Syndicate, your evil doppelgangers, reign, but Owlman schemes beyond simple conquest. The animation style nods to Bruce Timm; it's a DC multiverse story about accountability.