I use nb (https://github.com/xwmx/nb) and sync to gitlab. The best part of nb, is that you can bookmark a url, and nb will keep a copy of the page with the bookmarked url. So if the page disappears later, you still have a copy with your notes.
It's all stored as markdown, so you can go in and edit the page. nb also syncs automatically every time a note is edited.
Images, pdfs, docs, etc. can all be dumped into nb.
On mobile, I use gitjournal, and point it to the same gitlab repository, so the same notes are synced on mobile.
The next best thing is notable (https://notable.app/), which provides a much better interface, but doesn't do the download url thing. Gitjournal and notational-fzf also work with notable.
I've been using git as my storage and sync location for a couple of years now. Use it with Obsidian on my Mac, Working Copy is pulling and pushing the repo on my iOS device. At some point I also used the Gollum Wiki to have it available on the web as well.
It's just important to have automated triggers to push and pull things to avoid conflicts. That's possible with Shortcuts on iOS and there's a git-plugin for Obsidian as well.
I have small daemons for linux and mac that automatically push / pull from a git repository and sync my notes.
Its a 10 LOC bash script on each OS, it allows me to keep all my notes in markdown format, and use whatever markdown editor I want.
It allows me to sync any kind of content, not only notes, but also images, jupyter notebooks, whatever I want.
As a MD editor i tend to use Typora, but I might use VS Code, emacs, etc. depending on what i am doing.
I use about ~3 machines in total for work and personal time, and this works seamlessly across all of them. It allows me to keep my work notes separate from my personal notes, and e.g. keep them in our work's git servers.
