For manuscripts, I always do the first draft on paper then I type each chapter after it's complete. I do this for five reasons.
1. I find that it connects me more to the story than an impersonal computer screen. 2. It's easier to look back and reread what I've written, look for a piece of information, etc.. 3. I can make corrections while still keeping the original. 4. It's easier on the eyes. 5. The ideas flow more easily that way.