The one thing I assume based on no real knowledge whatsoever must be much better in the Snyder Cut is the action and visuals. Snyder has a signature style which a lot of people don't like much and honestly I don't always love it, either (though I did highly enjoy Man of Steel) but, with the sole exception of CG characters like Doomsday, all his dc stuff was a least good looking if not great looking as long as you can accept his style. The JL TC on the other hand was the ugliest thing I saw last decade and didn't have a single worthwhile action scene in it.