I heard, that BSD is dying...
OpenBSD - has a fanatical band of security obsessed users. Not going away anytime soon.
FreeBSD - It chugs along. Why is FreeBSD worth trying out ? See my reply above.
FreeBSD is more practical but for example you find the config files scattered about the file system whereas in NetBSD they’re always exactly where I expect. SDF.org has a great NetBSD system if anyone wants to try it out.
The thing I like is that almost everything I've invested in learning about it over the past 15 years still applies. Stuff that does change, or is added, tends to be done in a way that is sensible and consistent with established patterns and practices. Linux, not so much.
The reality of it is kinda like "Buffalo Bills will win the Superbowl this year".
With that said, with the decline of commercial Unix and the dominance of Linux, POSIX, in my opinion, has become less important, and in its place Linux seems to be the standard. I prefer the BSDs to Linux due to its design and documentation, but Linux has better hardware support, and the FOSS ecosystem, especially the desktop, is increasingly embracing Linuxisms such as Wayland and systemd. The FOSS BSD ecosystems are too small to counter the Linuxization of the Unix ecosystem, and I feel that Apple does not pay much attention to the BSD side of macOS these days.
I don’t expect the BSDs to die, but I do believe they’ll need to find ways to adapt to an increasingly Linux-dominated FOSS ecosystem.