ReactOS is entirely usable, if niche. GNUnet isn't usable. The home page describes it as "not ready for usage beyond developers", "still only suitable for early adopters with some reasonable pain tolerance", and "unlikely to provide good anonymity" -- it's unfit for purpose.

Hurd is an abject, embarrassing failure. Individual developers have produced more stable, complete operating systems as a joke (like PonyOS) than the entire GNU project has managed in 29 years.