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.