The Avengers was basically War of the Worlds with superhumans. So what does the Justice League boil down to in your mind? Is it super heroes in the Twilight Zone (think Men in Black)? Is it Clash of the Titans with the New Gods in place of the Old Gods (right down to the giant alien sea monster at the end)? Is it No Country Left for Old Supermen? I believe the theme of Gods and demigods is a good fit for the franchise; and sets it apart from The Avengers; with its armies of aliens and flying ships.