OpenBSD might not be the best choice for any given use, but it's so remarkably consistent and understandable that I think everyone interested in alternative OSes should try it out at least once.
used it as a webserver and VPN appliance for a couple of years now.
only thing in terms of maintenance is the following when a new release is released.
pkg_add -u ( i usually update extra packages every 6 months, which is mainly lets encrypt). syspatch sysupgrade
reboot:
after reboot
sysmerge to see if i need to do a config diff.
Has been rocksolid and very future rich in base aswell.
Always read the upgrade guide before upgrading.
This release only includes changes related to SNMP, which I imagine are irrelevant to most people, though probably exciting for a subset of OpenBSD users. https://www.openbsd.org/faq/upgrade70.html
The upgrade guide for 6.9 gives a better flavor for how OpenBSD handles and documents subsystem and configuration changes: https://www.openbsd.org/faq/upgrade69.html
Notice how succinct and consistent (across decades!) are the upgrade guides. The above have the same basic format and content as this one from 2004: https://www.openbsd.org/faq/upgrade35.html I've been doing remote upgrades of OpenBSD and Linux (mostly Debian, but also occasionally Red Hat derivatives) for over 20 years. While I've fortunately only rarely encountered significant problems with any of them, OpenBSD upgrades are the only ones where I can have any confidence in understanding and tracking how the system evolves across upgrades. Follow the upgrade guide and delete outdated files (much easier since sysclean(8)), and a 10-year-old OpenBSD box can have a filesystem as pristine as a freshly installed system.
I'm not one of those people who wants pristine for the sake of pristine. But pristine is important when you care about security, and maintenance burden is a huge component of security, as are simplicity and transparency.
For what it's worth, I think OpenBSD is intuitive because of its consistency. It's certainly been more intuitive to me than any other OS; it just makes sense as a whole in a way that no other OS quite does, and that's refreshing in a world where users are expected not to understand what their tools are and how they work.
OpenBSD just builds its intuitive bits on things you may not yet know. Fortunately, it has excellent documentation to get you started.
On OpenBSD, if you're stuck on something in ksh, cwm, pf or any other built in tool, the man page is right there. Easily accessible, easy to read and comprehensive. When I play around on my OpenBSD box, the man pages is often my first choice over a search engine.
Also, not confuse man pages on OpenBSD with Linux man pages. Those two are remarkably different. Many Linux tools have good and comprehensive man pages. On OpenBSD everything has great man pages.
To me, it seems worthwhile to have fewer 0-day bugs to worry about, and more reliable separation between user accounts (fewer privilege escalation bugs, etc etc). (I also recommend setting default umask to 0077 for the same reason, except while using pkg_add -- I have a wrapper script that undoes it temporarily for that due to issues encountered.)
There are reasons people use Windows or Apple (perceived convenience), and reasons not to (long-term cost/benefit decisions for known uses).
In case it becomes useful to anyone: One way to traverse the docs is (occasionally helpful) is using something like http://man.bsd.lv/ for OBSD docs, like putting in an "=" (w/o quotes) in the search field then clicking "apropos" shows all the commands -- a useful way to learn "what is available in the base system"; or doing full-text searches (can be learned locally, I have an awkward script for it if needed),
(Edit: s/what is available/what is available in the base system/ .)
And: I find the ~"only 2 remote holes in the default install since about 1996" to be very impressive.
Edit: Another way to look at it might be by priorities. I have come to see priorities of some systems roughly as:
OpenBSD: security, openness, correctness (including of documentation), portability.
Linux: features, performance, openness, breadth of everything, compatibility, convenience (distributions vary in specifics of course; debian and/or devuan continue to impress me in their own way).
FreeBSD: performance, stability, openness.
NetBSD: portability, stability?, maybe enjoyment for its developers, openness. (I know least here.)
Windows / Apple: profitability while targeting preferences of specific groups who want different specific kinds of convenience, it seems.
To me OpenBSD is similar to what Slackware was, as simple as it possibly can be, with the advantage of a BSD being coherent and consistent.
I'm a long time Linux user and only used OpenBSD recently. I often find myself Googling Linux configs. I did use Google for OpenBSD to get started but found after a day I wasn't and relying on the man pages instead for system settings etc. They really are short, concise and complete, everyone says this but until you use them it's hard to understand.
I use Emacs I don't know Emacs. Emacs is a completely different beast to OpenBSD. Emacs is a huge rabbit hole and you spend as much time building your own Emacs as you do using Emacs. OpenBSD i've set up once which was simple as someone never using it before, and then forgot about it. It's been sat ticking away in a corner, no interruptions.
As much as I really like OpenBSD I don't think I can use it as a primary desktop. There's a few compromises on hardware support, no docker for my day job and I've read the desktop experience is slower than Linux just because it hasn't had the money and people Linux has had with drivers etc.
I'd really recommend anyone try OpenBSD for it's simplicity and educational purposes. If you use it as your main OS you will likely be dissapointed with some of the limitations, as a server / secondary educational device you might be pleasantly surprised.
Unfortunately search engines are unreliable, some "search engine optimized" virus pages could be first, and not some bank or docs website.
Luckily, the manpages are available on your favorite search engine!