Overally I'd give ZS Justice League about a 7/10 while I gave Josstice League about a 6.
The theatrical was your usual boilerplate, run-of-the-mill, forgettable comic book romp that Marvel have thrived on and although that cut was all over the show, I put it down at the time to just bad filmmaking which even Marvel can be guilty of. It's not a DC vs Marvel thing, they also have some perfectly average movies I can barely remember anything about, Thor 2 anyone?
When this came out, what really stood out most to me was the fascinating story behind it all; they cut out a LOT of material, basically an entire movie, and recut it to something you can barely even call the same move. That's been fascinating viewing experience, and there's never been an example of that in this sort of scale, maybe it will start a trend?
ZSJS is a superior movie, by some distance, but it's short of a great movie. This time the tone is consistent, the movie invests in it's characters, and some of the visuals are actually quite spectacular. Although the plot was basically a rehash of Avengers IF, I was invested in the movie and keen to see it through, run time didn't bother me.
But it also has it's usual Zack Snyder problems of missing a human touch and soaking for too long in it's loud, dreary and joyless mood. Nowhere as bad as BvS but definitely cut from the same cloth. That's where Whedon got it wrong though,goofy and quippy isn't the answer least of all for this movie; TDK is a good example of taking serious material and applying to realistic human characters. The epilogue is just a giant wank.
I'm glad we got the chance to see it, this was an interesting exercise in how 'movie by committee' can drastically alter film making.