OpenBSD and have used NetBSD as a sdf.org member for at least a decade.
Discussion
In terms of functionality and enjoyment how would you rate your experience with BSD?
NetBSD hands down the most fuss-free OS for webserver things I have ever used. Not once have system updates ever broken my server. It "just worx" and you don't have to fiddle with things once set up.
OpenBSD is great for security minded things - it can be a bit finicky when trying to build things you'd use on a normal daily driver (which is why I still Gentoo and build own kernels) but it seems to get more usable with each release.