OpenBSD is in fact already pretty much user-friendly. Installer is simple, althought an a textual interface. It comes with preinstalled X server and window managers fvwm and cwm. In the installer you can choose Xenodm to start automatically after boot, it would be your display manager and you can just simply login through it to fvwm. From here you can edit .xsession and choose any window manager you installed or pre-installed cwm.