I generally use open office and save in .odt (I'm talking about on a pc/mac - I don't write on my phone)
For me it's a matter of steps or progression. First by Hand... then rewrite in Word (which is basically the first edit, where I add more, remove, etc). then to GoogleDocs where I can edit it and share with some other people as beta-beta readers.
I use Google Docs ir pen and paper for work on the go and at work when it's quiet, but when I get home I transfer everything onto Scrivener. I avoid subscription software because I fail to see how the concept is justified over a licence agreement for domestic users. Truth be told the only reason it's installed on my laptop is because we have access to university accounts still and they give it away to students and teachers for free without anything other than a university or school email account as proof. I favour open source software more in these cases.
Word is cumbersome, particularly with style support. Google Docs I have limited experience with, although I did have a Chromebook for a while. More important are things like the process of creativity and what you have to say. And, of course, whatever you use, don't trust it. Keep backups, at least one away from your home. Consider exporting a copy of what you write to a plain text file. If you had to, even if you think plain text writing is on the level with quill and iron gall ink, you could pick up and continue working on your piece with just about any editor on any computer.
I've always just used Word and never had a problem with it. I've never used Goggle Doc, and never plan to
I haven't used Google Docs in years because... I no longer trust Google. I prefer to disable my network connection when writing. Web apps are slow and clunky compared to native desktop apps. The WYSIWYG approach gets in the way unless you're ready to print. I don't use Word because... Word doesn't run on OpenBSD, except as a web app -- and my objections to Google Docs also apply to the online version of Word. I have to deal with Word at my day job, and it's clunky and unpleasant to use. LibreOffice's implementation of Track Changes is good enough for me to be compatible with editors who insist on having manuscripts formatted for Word. Because I'm a software developer at my day job, and because I got exposure to Unix early in college, I prefer text editors like vi and Emacs when composing drafts and doing revisions prior to submission. It's OK if you haven't heard of these; if all you want to do is write some text, Notepad will do.
I think Google Docs is more promising to me as compared to Word. It is easy to do formatting in Docs.
I used to do everything on Word, but now I'm leaning more toward Google Docs because i can access it from anywhere. I didnt start out wanting to use it. I started out copying a paragraph from Word on to Google Docs so that I could tweak it at work....then i just kept writing and writing. So that particular one is now stuck in Docs lol. I mean, eventually I will transfer everything back to Word, but Google Docs right now is what I'm using. I do, however, have a separate Google Drive that I have saved my Word files on. I started doing that in college when my computer crashed and I lost all my homework assignments and research papers (that was a hellish few weeks). IT services on campus suggested Google Drives and saving my work in it. So I've been saving my stuff in Drives. Havent used Docs really until this year. Now its a norm for me.