I've used Outline for 2 years. It's honestly really nice. Pretty simple to selfhost and you can set-up internal auth with something like Authelia.
However I recently moved to Obsidian.md because of the large community and add-ons available. I love it. For device synchronisation I use Syncthing and I can't complain. It has no WebApp but it's available on every platform
I love outline as much as the next guy, but calling it simple to selfhost is a bit of a stretch. It has lots of moving parts and not having an auth solution built-in makes it not suitable for the average user.
That said, it does beat other wiki solutions by a wide margin!