I'd prefer something that runs locally,I don't think I'd want to use some kind of office oriented word processor, and I don't imagine something like VS code would be the right tool, but open to suggestion from the experienced out there!
* FocusWriter is a nice, configurable distraction-free editor/light word-processor.
* I hear good things about Scrivener, which seems to be like a really good code editor for prose.
Personally, I write in Vim + HTML (which is a pretty full-featured and reasonably light markup language if all you're doing is writing).
For writing on the phone its Google docs. Then copy over to sublime.
Everything is checked into a git repo.
Some are markdown formatted for publishing.
Low-tech. semi-automated. Works for me TM