You seem to imply that security will always result in less speed or less usability, and that is not always the case. The thing with OpenBSD is that security will always come first between the three values when they clash, but they don't always clash. And yes, it is the most secure OS out there if you are to judge by the statistics over its history. I'd say that only two remote holes in so many years pretty much grants them the "secure by default" label. Maybe looking from outside it seems like security is all they think about, but my impression is that it is more about correctness and simplicity, and that security comes as a consequence. As an example of simplicity, I am not personally aware of any install that is so simple as theirs. Except maybe ubuntu's, but then with ubuntu you end up with a mess of interdependent packages and it will be a hell to uninstall shit you don't need.