The Justice League 2021 Zack Snyder cut is the larger than life masterpiece, the true original in all its glory, like a Picasso, A rembrandt, or a Salvador Dali painting. it really made the Joss whedon cut look like the cheap knock off that you buy in the corner of a dark alley.
as a romantic writer once wrote - how do you count the ways? How do you count the ways in which the Snyder cut is so much better than the 2017 release? Let's try:
Plot - who would have thought that adding 2 hours to the film, resulting in the 4-Hour work of cinematic brilliance, would allow for things like better story development, plot enrichment, Superior character development, prolongation of dramatic moments, way better fight scenes, and a massive surprise ending that will delight everybody? Zack Snyder knew it, and now we do too.
characters - the Snyder cut has elevated flash and cyborg to The prominent roles they were always meant to play in the film and story. Flash, portrayed in the 2017 release as a dopey, dorky kid who couldn't get anything right, is finally revealed as the central piece in DC's plans to create alternate timelines which is Central to the comic book mythology. Cyborg, who felt like a knockoff iron Man in the 2017 release, is now portrayed as one of the most powerful members of the league and most likely Central to any of the future successes in the future wars.
editing - the editing in the 2017 cut was so disjointed and clunky, that it really felt like a film that was put together by surgery in a trauma ward of an emergency room. The 2021 cut is beautifully edited, not in small part due to the extra time they were given. The editing here felt like a real literary work of art, comparable to Lord of the rings and game of thrones.
in short, with the Snyder cut of Justice league, DC has announced to the world that it is finally ready to compete with prominent marvel franchises like iron Man and the avengers. And marvel should be worried. if DC follows the same template for future releases, marvel is going to have a lot to live up to in terms of cinematic competition for years to come.