Hi Simi,
All great questions. The files are on my folder, and I currently use github - that's because I like to keep versions as I work through my manuscript.
I find VS code the fastest to write with its autocomplete, intellisense plugins, and Markdown helps me work unobstrusively focused on text and nothing else.
Finally, PQ lets me do a lot of stuff that cuts manual work (the docx conversion is just one part). For example, boxsets, updating backmatter material across the catalog, improving the look-and-feel of the catalog and so on, and it works great.
I've tried scrivener, and it wasn't for me. But like all things in writing, the workflows and choice of tools is personal and this route has worked for me for quite a while now.