While studying at the University of Copenhagen, DIKU.dk we used Unix systems - the sandbox it was called and I liked it. I wanted Unix at home, but at the time a SCO Unix would cost about EUR 2000 and my machine was much too small for it anyway.
We could borrow Minix and install that, and it was great fun, then came some information about 386BSD, also that it might core dump across your hard drive if it had some problems ;-)
I used Linux for some years, and still do, until I decided to look into BSD - having read how Linux and the rest of the world got TCP/IP from that, and some systems at DIKU was running various BSD versions on MicroVAX. Having decided that I tried FreeBSD, NetBSD and OpenBSD, and fell in love with OpenBSD immediately.
The simple way everything works and the nice - simple - installer was a bliss. I think we are talking around early OpenBSD 2.something.
More or less from this point forwards I have used OpenBSD for laptops, servers and my private mail server has been running OpenBSD for more than 12 years (my son is 12 soon and I had it before he came to be). To this day I cannot think of anything as simple and elegant as having OpenBSD and Postfix as my email system.
Professionally I have also used OpenBSD for lots of "infrastructure devices", need a console server, whoops Soekris-5501, 4-port serial, OpenBSD, conserver - done! Need a nice DNS server without the fuzz, OpenBSD install, start named - done. BTW having NSD in base sounds interesting.
OpenBSD does not really get the fame it deserves, and unfortunately since it can out of the box support so much - and in so few MB of space.
Keep it going! I try to support by buying each new set to get the stickers, and have usually installed it before they arrive :-) I also have a nice collection of OpenBSD clothes.