Tailscale has a higher quality application, codebase and backbone, and also more generous free-plan limits.
Tailscale free: up to 6 users, each with unlimited devices (used to be 3 users)
I use Tailscale because it's professionally supported and better implemented. It has a much smoother UX compared to ZeroTier. It's also been profesionally audited, while ZeroTier has only sworn since 2020 that it'll totally be audited at some point after 2.0. ZeroTier may be a smaller target, but that also means it has less of a track record.
Also, I don't use Windows, but I don't see how that'd have anything to do with this.