Check out what users of /r/freebsd have to say about the pros and cons of FreeBSD over Linux. This lengthy discussion has this particular post voted to the top:
The main advantage for me so far is root/boot on ZFS out of the box without much effort. Data integrity matters.
pfis a decent firewall and I use it everywhere.
Also, dtrace. It’s kind of a big deal.
Other than that there’s not much that directly matters to me. Some will talk about the BSD system model and tight integration of packages and so forth but from the user perspective I don’t notice much difference, aside from fewer packages being available for BSD. I use BSD for fileservers and routers and am very satisfied. Linux everywhere else currently for applications, like web/database servers, or virtualizing our Windows systems. – /u/IBSUchild
Full discussion thread: https://www.reddit.com/r/freebsd/comments/45jx1r/advantages_of_freebsd_over_linux/t1_czyj133