Probably Slackware. Quite similar to OpenBSD although I did have a hard time with driver support. But if I remember correctly, installation was blazing fast and you'd get a barebone system up and running in no time.
I was pleasantly reminded how much Slackware still resembles BSD in how it configures things and it's emphasis on a minimal install that can be added to as needed. Other than new apps, a few improvements and, of course, updated hardware support Slackware has changed surprisingly little since I used it in 1995!
Patrick Volkerding is a great maintainer and I really appreciate his efforts over the past few decades!