This link is for OpenBSD but I have the most experience with FreeBSD. Reasons to try out a BSD, even FreeBSD:
1. ZFS -- by far and away the best filesystem there is. (A hella partisan take but try it out and you'll likely fall in love like the rest of us did)
2. The handbook. The handbook is gold. It's up there with some of the best documentation available.
3. Less fragmentation. The BSDs have 3 main derivatives: NetBSD, OpenBSD, and FreeBSD. (There are others but these are the main)
4. If you like LXD then you'll love Jails.
5. The BSD license. (If being the most free means something to you. I kind of like it but maybe this isn't a selling point.)
6. Can be rolling or used in an LTS fashion. It's rather easy to track -current all the time or just stick with a stable release and do periodic binary package updates.