I’ve found that a combination of the two is most comfortable for me. I make a rough outline of the story’s basic foundations (such as the major plot points), then I free-write the in-between stuff. It’s almost like drawing, I think: drawing freehand can be fun and all, but your proportions sometimes come out a little wonky without any guidelines. If you’re going for a stylized look, that’s perfectly fine. But if you take the time to sketch out the basic shapes before you start drawing the form, it will look a lot smoother when you’re finished.