OpenBSD or NetBSD would be better than Linux if you wanted to delve into operating system internals, or you wanted to operate the OS at a more direct explicit level. They are more straight forward in their implementation - modern Linux has more layers of abstraction (udev, dbus, systemd etc) which are useful but more complex.
Other than that, it mostly would come down to licensing or subjective taste questions.
Other than that, it mostly would come down to licensing or subjective taste questions.