I chose Joplin over Obsidian because they offer webdav sync and it’s trivial to set up sync with a synology NAS. Obsidian doesn’t offer it as it competes with their sync commercial offering.

For a long time Joplin's support on Android was buggy and late on releases, it's why I switched away. Is it better now?

I am of the opinion that there isn’t really a good editor for Android, but Joplin is probably as good as we’re getting. (I love iA Writer, but it’s not as good as it could be on Android.)

I think the sync server is Joplin’s secret weapon on this front. I tried using Syncthing for managing my docs for a while, but I think having a dedicated sync server helps on mobile. I found using alternative sync methods was too wonky on a mobile device.

Syncthing on android works for Joplin only to version 2.5.

I’m speaking more generally. (As in, I used Syncthing to sync actual docs to a folder on my phone.)

But Joplin above 2.5 version wont read those synced data.

You can run a separate Syncthing instance and directly link it through the file system, which is what I meant.

Sure, but Joplon above version 2.5 wont read those data.

It works fine for me. I've used it moderately and never had issues.