You raised an interesting questions, Paeter. My assumption is that it's based on the ultimate edition, because that's the movie Zach Snyder always intended to make, but I don't have any evidence to support that.
I haven't watched it myself yet. I'm planning to do a deep dive into this movie for my podcast some time soon, and I'm still trying to figure out how muc I want to go in fresh with just my own ideas, and how much I want to draw from other sources (such as Snyder himself). I don't want to just parrot what Zach says, because there's no value in that. Perhaps I do it fresh, and then listen to Zach's commentary, and then add some additional thoughts afterward.