Joplin has been fantastic so far -- it offers so much value (cross-platform, reasonable design, markdown support, search) for completely free, and with easy sync options and no feature gates. It needs to get mentioned more.
It seems like productivity apps are the wave now, but Joplin is exactly what I wanted -- a simple cross platform note-taking app.
I'm considering hosting a Joplin WebDAV/S3 sync + backup service for something like $1/month billed yearly -- I wonder if people would be interested. Obviously most people probably just use Nextcloud/Dropbox/OneDrive and there's no real reason to trust some random sync/backup service over the other options, but with encryption turned on, the place you sync to doesn't matter and it feels like people might be interested.
It works on my phone
It works on my computer
It syncs to a cloud provider I specify
It looks like the API it exposes is fairly straight forward for building on top of.
There's a lot to like. True, like a lot of small open source projects, there are some rough edges, and progress is slow, but I believe they welcome new volunteers.
There are, however, a TON of note taking apps floating around at the moment. One is Roam. Roam is very expensive ($15/month; a premium price point in a space that's mostly free or a couple of dollars at most), and has a bit of a...well, almost cult-like atmosphere around it. People that like Roam seem to love it, for some reason. On the other hand, development is fast, and they support TONS of features. Backlinks seems to be a big one. Notably I think Roam is more focused around "blocks" of content than around freeform markdown.
Other options include Notion, Bear, Obsidian, Tiddlywiki, Evernote, Quiver, Dynalist, Workflowy, Standard Notes and many, many, many others. All are excellent options in this space. And now, Athens, which I suppose is trying to be a better, open source Roam?
Honestly, if you care a lot about note taking apps you should dig into it, there's a ton of options and interesting tradeoffs. And if you don't, then....eh, probably doesn't matter much.