Syncthing is under my "want to like" list but I gave up on it. I'm a one person show who just wants to sync a few dozen markdown files across a few laptops and a phone. Every time I'd run it I'd invariably end up with conflict files. It got to the point where I was spending more time merging diffs than writing. How it could do that with just one person running it I have no idea.

If you just need a Dropbox replacement for file syncing, Nextcloud is fine if you use the native file system integrations and ignore the web and WebDAV interfaces.