I do know that if you try to be honest with your story and not force it into some particular desired shape or other, you'll probably be better off. Or, conversely, be technically skilled enough to start with the perfect desired shape, and then mold the story into that shape from the beginning. To me it seems the second option is a whole lot harder to manage, but it may depend on the author.
Sorry, for the double post; cut and past went odd there.
I was going to say, this seems to be an either/or based on ways of working that exclude a middle that has been feeling to work for me.
Which is, that I usually start with a key scene or scenes and know how they should play. And the very
first thing I ask of a character is "is this a person who
will, absolutely utterly to the core of who they are,
have to behave the way this scene needs when it arrives ?" There's no forcing story into shape there, nor is there molding story to shape, because the shape of the story and of the people depend on each other so thoroughly that it can't be any other way. (Bits in between may flex, but the key scens don't.)
I strongly recommend Daniel Abraham's Long Price Quartet because they make this particular angle very visible. They are set in a not-like-anything-else fantasy world with distinct and unique cultures and magic, and the people in it are really amazingly perfect products of culture and surroundings such that it's impossible to believe people like that arising in any other setting or being anyone else than who they are.