I was using SyncThing, and it worked, but any time you have an Obsidian vault open on two devices, or shortly after another, you're always thinking about if you're going to have to clean up a bunch of sync conflict files later. And that mental overhead is not worth saving $4/mo.

The conflicts are never hard: it's like a git merge conflict where you just take the latest of every conflict block.

For me using SyncThing totally worth it, but I guess it's down to our income difference

I used multiple sync "solutions" (terrible idea, in retrospect); Dropsync, Syncthing, Drivesync, in addition to paying for Obsidian Sync, because I was delusional about "backing up my data". Huge mistake on my part, I've spent many, many, many hours deduplicating worthless "backups". Agree with "just pay for Obsidian Sync".

Mirrors my experience.

What tool can be used to resolve syncthing conflicts? I get a lot of.stversion files.

I try to selfhost most of my stuff I rely on. Immich, Vaultwarden, etc. I gave up on trying to selfhost sync solutions for Obsidian - Obsidian Sync is just so damn frictionless compared to all other solutions. Also, it feels good supporting the development of Obsidian.