I'm not sure. If I had killed the character off, there would have been wails of anguish and gnashing of teeth, no little of it mine. But at least one reader said (and I agree with them) that the story would have been equally satisfying either way, in the 'This is the proper way for this story to end' kind of way. Even the character death ending wouldn't have been utterly bleak and hopeless; I just don't do utterly bleak and hopeless. Well, no, I lie - I've written at least one story, from the POV of a teenage boy committing a very gaudy suicide, that was utterly bleak and hopeless - but that was just because of the particular POV it was in. The world in which that character existed wasn't any better or worse than any other.

So my decision was based (I hope) more on "What is the most true-to-character thing for X to do, given their starting place in canon and their subsequent character development in this series?" and "What resolution will best advance the theme of this story and the series as a whole?" and "Am I repeating myself and/or Joss Whedon?" And also the fact that I'd already written other stories which took place later in the same continuity, and so I was to some extent constrained by those later stories events as to whom I could kill off with impunity. Though in the Jossverse, death is often merely a minor inconvenience, so I could have gotten around that if I'd really wanted to.

I suspect that a given reader's estimate of the literary worth of either ending would depend on what they saw as more admirable - a character who bends, or a character who breaks.