Why not have them both be "right," according to their own value systems anyway, and then have the end-game slideshow in both branches tell the player the story of what they did from the perspective of the other side?
This would ruin the point I'm trying to make.
You don't have to make both branches equivalent. Both of them could feel "right" from inside, but only one of them could contain an information which makes the other one wrong.
In one ending, the hero only has limited information, and based on that limited information, the hero thinks they made the right choice. Sure, some things went wrong, but the hero considers that a necessary evil.
On another ending, the hero has more information, and now it is obvious that this choice was right, and all the good feelings from the other branch are merely lack ...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.