Copy/pasting my spoiler tagged post in the OT, but also adding some to it:
I've been playing this game entirely with my wife as an audience and she was annoyed that I chose Verso at the end. We ended up having a debate about it during the credit roll because she thought I should have sided with Maelle since I had spent the entire game with the cast of characters from the painting.
My argument was that the game was clearly a lesson in learning to process and manage grief, not hide from it through escapism. Aline/The Paintress' escapism into grief is what started the entire chain of events and caused countless tragedies both with and without the canvas. Alicia/Maelle was allowing her grief and guilt -- for her role in Verso's death and her disfigurement in the real world,
and the loss of the 'people' of the canvas -- to dominate her emotions, which was the same kind of thing that clouded her mother's judgement.
At my wife's request, I loaded the save just before the canvas choice and chose to side with Maelle, and it vindicated my original decision. The Memory of Verso was being exploited as a puppet to keep the canvas alive. Verso pleading for Maelle to end his life, end his suffering after she defeats him was haunting. The way he looked defeated in the Epilogue because she had clearly 'repainted' him to be a constant pianist in the Opera Hall. The very last shot we see of Maelle with her face paint/chroma distorted like her mother's had become proved that Maelle had turned into the same kind of monster her mother had been, manipulating the canvas for the sake of her own happiness at the expense of Verso, and her real world family.
Thinking back, this was sort of telegraphed during the Maelle relationship quest with Painting Alicia in the Reacher when Verso had a blow up with Maelle about Gommaging Alicia without talking to him. I'm paraphrasing from memory but I believe he says something like "You Paintresses do whatever you want without considering the feelings of others."
I've seen debate online about "good" or "bad" endings. I feel like this is a game where there isn't really a "good" ending. There was going to be loss either way. But, personally, I think choosing to side with Verso and end the painting is the
right choice. Maelle's choice is denying reality and living in mental delusions.
But from what I understand you can't fight the final boss again to pick a different ending. This is simply where endgame starts to clean up with the locations and boss fights (and a New Game Plus option shows up in the pause menu).
If you go into the menu and select "load previous saves", scroll down a couple and you should find one where it autosaved just before the choice. On mine it was 4 save slots down. Though if you play more in the post game it'll eventually drop off.