I first used my Gmail Drafts folder. This was actually really good for a time. Accessible via web or phone, the Gmail app automatically syncs the drafts to any device. However with many notes this gets messy.
I moved to some startup note-taking app after that. I can't remember the name now but it was fairly perfect. Unfortunately they closed down. This was the time I really started lookin triedg and trying many different things.
I settled on plain Markdown files stored on Dropbox. I use the excellent Draft app on Android to edit on my phone, and vim on PC. The only drawback with this, Dropbox's text renderer doesn't do fenced code blocks, so it looks funny on the webpage if I share a note with those.
I have a note-taking nerd friend and he settled on a private git repository.
I've tried Evernote but I hated it.