At $4 per month, I don’t consider it expensive at all to have this whole category of problem solved for me. Mobile app, desktop, laptop synced flawlessly and quickly.
I'm biased but I'd say the benefits over Google Drive are: 1. end-to-end encryption, 2. seamless integration with the app (e.g. version history), 3. granular control over what settings and files are synced for each device, 4. shared vaults.
In addition Obsidian Sync helps keep Obsidian 100% user-supported. Obsidian is not subsidized by advertising or any investors. And you can actually contact the team if you need help. See also: https://stephango.com/vcware
I'd pay for the option to host my own server with the official sync but they don't offer that for now.