He doesnt like Marvel movies.
When suggesting that Batman and Superman are immune (at least to a certain degree) to genre fatigue and saturation, Snyder suggested their mythological status in American pop culture is a shield. He also apparently views that as the reason why Marvel has a bigger problem with its technically less iconic characters (not named Spider-Man or Wolverine, anyway).
“It goes to the mythological nature of the movies that we’re making,” Snyder said to The Daily Beast. “I feel like [Spielberg’s] right. But I feel like Batman and Superman are transcendent of superhero movies in a way, because they’re Batman and Superman. They’re not just like the flavor of the week Ant-Man—not to be mean, but whatever it is. What is the next Blank-Man?”
If you don't want to say hate? Fine. But he definitely wanted to go a different direction than Marvel. Justice League has Avengers finger prints all over it. Come on.