I love OpenBSD, have been a user (including professionally) for over 2 decades, and appreciate their stubbornness when it comes to security (including sacrificing performance), but for work for anything other than a layer 3/4 firewall I'd use FreeBSD (FreeBSD has an older, threaded version of PF, though). It's got ZFS for storage, a much more robust threading system (meaning modern multi-core processors will be better taken advantage of) and generally has broader support for hardware.

Pre-2005 running FreeBSD was a nice little "secret" that allowed you to run a rock-solid OS without drama or headaches. However, professionally nowadays I've accepted the fact that linux "won" and I don't want to deal with the headaches of finding people that can admin something niche, on top of so much tech tooling being designed on and around linux. Most of my work is done supporting docker containers in some way, so why fight even if it's possible to run docker on FreeBSD...