Batman's final showdown with Owlman. Even though Owlman is Batman's equal in fighting skills, and is using Powered Armor, Batman manages to survive pull off a last minute win by sending Owlman and his bomb off the icy alternate earth.
It's also a Genius Bonus insult too: Throughout the movie, we've seen that Owlman is a classic nihilist, someone who clearly would be a fan of Nietzsche. Nietzsche is credited with the line "When you look into the abyss, the abyss looks back at you," so not only is Batman utterly defeating Owlman, he's mocking his philosophical standing at the same time.
And just for a hat trick—Batman didn't just pick the frozen world out of nowhere. Superwoman described it to him when she was taunting him during their fight, which is how he knew to look for it in the first place. Batman had to send the bomb somewhere, anywhere was better than Earth-Prime, but he still took the time to make sure he didn't sacrifice the few for the needs of the many, and he did it using a thread of information from a villainous monologue. Ladies and gentlemen, Batman at his best.
The fact that Batman fights his way through half the movie with a broken rib.
Batman: Careful, Aquaman! They're stronger than you are.
Aquaman: That remains to be seen.
Even better, since it's soon shown that Aquaman is demonstrably stronger than Captain Super.
Batman takes on the Super Family in a power loader. Yeah, he ends up getting pounded, but it's still awesome.
When Good Lex reveals the blue Kryptonite (Ultraman's weakness, as opposed to green Kryptonite for Superman). Never before has the ever-predictable Kryptonite reveal from a Luthor ever seemed so awesome.
Ultraman: Blue... Kryptonite!
Lex: The only thing that can hurt you.
Ultraman: But... I...
Lex: Destroyed the last piece on Earth? True. But I've been visiting other Earths.