I only saw Whedon's Justice League once, in the theater, so I honestly can't compare the two that well at this point. I didn't care for Whedon's version, but this version had lots of problems too. I can't say whether it's "better," but at least it's Snyder's version, not some hybrid slapped together.
I'll just highlight a few things that stood out to me:
* I'm not sure this movie passes the "Bechdel test" - where two women have to have a conversation about something other than a man. The scene between Martha and Lois made me think of that in particular, especially since it ended up not even being a conversation between two woman (what purpose did it serve to have it be Martian Manhunter in disguise? Felt problematic to me). I don't recall if any of the Amazons' conversations would pass the Bechdel test - it's possible they did, but I feel like they didn't.
* While the CG wasn't bad in general, it felt like every scene, even those that were presumably actually shot outside, looked fake. I think that's intentional by Snyder, as he's tried to emulate the look of the source comics in other films like The 300 and Watchmen, but it tended to take me out of the movie.
* The writing and tone in general were flaws in both Snyder and Whedon's versions. Snyder goes for very bleak tone - even with the injected humor attempts from the Flash and Aquaman - versus Whedon's more playful overall tone, which is also reflected in the visual color palette of each film. Neither really works that well. It seems no amount of reshoots or editing could really fix the actual writing. The flaws are in the script. But I did enjoy some of the lighter elements in the Snyder cut - at least the Flash and Aquaman seemed to have a bit more character than others, particularly Superman.
Speaking of Superman, I just don't care for his characterization. He just seemed wasted in this movie. Even in the relatively little screen time he had, he felt very flat.
I didn't hate the movie (some parts, I definitely did), but I don't really have too strong of feelings about it. It just exists to me, nothing more.
I feel it's really hard to judge this solely on it's own merits, given that it's attempting to redo a film that someone else took over.