One of the great things about the three Making of Star Wars books is how it shows the movie evolved from the first drafts of the script. While there was one of these made for The Force Awakens, and its release forever cancelled, it’s likely we’ll never get one for Rogue One. However through interviews over the last few months there is enough information to at lease piece together a general idea of how the movie evolved.
The first draft, the Whitta one, was never filmed. This is the one everyone has been talking about lately where Jyn and the Cassian-type character survived and Vader killed Krennic. Fan favorite characters Baze, Chirrut, and Bodhi didn’t exist yet as it’s likely the crew were closer to the concept art above, which some people consider the “Knoll cast”. From the “Art of” book we know that Vader’s Mustafar fortress originated in this draft.
Following that version of the movie would be the Chris Weitz draft, and that’s probably closest to what was actually filmed. Cassian, Baze, Chirrut, and Bodhi are all here, although it’s still very different than the version we ended up with. In this version the interrogation of Jyn is the first thing we see after the intro, and she’s was much more of a jerk to the Rebellion (thus the I, Rebel line). This is likely where the ending was much longer with the Death Star plans in a different building from the transmitter and the crew had to run to beam them out:
We know they filmed a death for Cassian where he and K2 died next to each other against a facility door outside, so it’s probably that’s from this draft of the script:
So that brings us to the infamous reshoots when the Gilroy brothers became involved. It’s here where the introductions to Cassian and Bodhi were added before Jyn is taken to Yavin 4. It’s also where the superior ending was crafted, and probably where the fan-favorite Vader slaughter was added at the last minute.
It really feels like there were three main versions of Rogue One: the first draft that was never filmed with a happy ending, the version filmed, and then the final movie that was the result of extensive (and successful) reshoots. And if you go back and read those Making of books for the Original Trilogy you’ll see this really isn’t that uncommon when it comes to Star Wars. George’s first draft of A New Hope was drastically different than that we ended up with, and the Leigh Brackett version of Empire was famous for how weird it got at certain points.
Rogue One will forever have the stain on it from people overreacting over standard reshoots, but the result of the tweaking and evolution of the movie was one of the best Star Wars films.