Unfortunately, most of the answers that I have seen come down to saying one and the same thing, namely, that a BSD is better because its userland is "part of the OS." Though could be true, this is not very enlightening.
I've read some other stuff, too, though, such as praise for the ports system and FreeBSD's "jails" feature.
But I imagine it's a little like Linux distros. If you don't already use Linux, it's kind of hard to understand why anyone cares about the minor differences between distros.
* https://www.freebsd.org/cgi/man.cgi?query=ps
ps has one set of options and has used getopt() since April 1990.
* https://www.freebsd.org/cgi/man.cgi?query=inittodr&sektion=9
Documenting the operating system encompasses documenting the kernel as well.
* https://docs.freebsd.org/en/books/handbook/
"Part of the o/s" is not the best description. The idea is that there is a clear demarcation between all of the programs that come as part of the operating system, and all of the programs that are applications softwares that are installed on top of the operating system.
At some point you just have to commit enough effort to try it out and experience the difference, or just be happy with Linux. After all if you're happy with Linux, then BSD's userland is part of the OS isn't a fix for you. But if working with Linux leaves you with this weird itching sensation in your brain that there should be a better way, give BSD a shot.