Honestly, the biggest advantage OpenBSD has always had for me was its internal consistency and excellent documentation. If you’re a heavy command line user, you can usually figure out either what command you need to run or what you need to look up in the man pages. It’s also great for C development, as it has far better docs for libc than glibc does.

If you have supported hardware (and that’s a bit if and caveat; smaller than it used to be, but still quite large), then everything just works. Even little things like the built-in screen brightness buttons, just work regardless of if you’re in x11 or a terminal (same with volume buttons), because it’s designed as a complete system rather than a distribution of otherwise unrelated open source projects.