OpenBSD is the place for me to start. It’s not the fastest of the *nix variants but it is reliable and Restricted by default; the 4th and 5th R(s). With my early introduction I believed that the OpenBSD team was small, selective, and secure; the 3S(s). The team does not typically keep a lot of useless code around and they prune the code every so often. They are fanatic about excluding code that might have some restrictive licensing, failed to be open source, or otherwise limits what the user might need or wat to do. Sometimes that means that various projects are excluded, or are removed but if you follow we are moving to the R(s).