I think that a degree of autonomy and character choice is vital, simply because without that, there’s no real story or conflict, and everything falls flat. Ideally, at least one character needs to have some level of choice/control over the outcome, be it the person making the change, or the people being changed. I think the best stories tend to hit a bit of a sweet spot, where the characters lose sense of their old selves, even as they transition into some sort of new life. The result is a real crisis of subjectivity–without knowing who they are, they can’t even begin to answer the question of who they want to be. Those are my favorite kinds of stories myself.