I haven't completely switched; currently I have machines running linux, netbsd, macos (yeah i know)......but one of the things I appreciate about each BSD is the simplicity, documentation, and how each BSD is cohesive. Only thing lacking is support for newest hardware, especially wifi. I know FreeBSD has hired someone specifically to improve wifi support.
I still use linux (Debian for the most part). I'm used to it, my hardware supports it, and keeping it updated is straightforward. However, I don't like how every distro is just debian (or buntu, or fedora, or arch) with a different face. The diversity in linux is a pro and a con to me. I stick to vanilla debian or BSD.
FreeBSD: I like different features like ZFS and boot environments. Also, ability to run linux programs if necessary is nice. Most support so that's helpful. Pretty powerful OS as well as stable. Has other neat featurs like jails, bhyve, poudriere that I haven't really explored. I do sometimes wonder if FreeBSD is starting to stagnate as a project. I hope it doesn't obviously.
OpenBSD: great documentation. On hw like a thinkpad, everything just works. Lots of neat tools/utlities created by developers. security innovations are great.
NetBSD: maybe the friendliest community I've encountered. Really versatile OS, lots of features. Really impressive when you think about how small the project is. Oh and pkgsrc. Weirdly, I find it to be a good compromise between Free and OpenBSD. I would like to see documentation improve somewhat, but I know there's only so many people working on the project. If I knew more about technical writing I would consider chipping in.