As an OpenBSD fan: consider Qubes instead if you want a "desktop" experience. OpenBSD works fine, but the open-source desktop is quite vulnerable (consider how many things need to go wrong for
https://scarybeastsecurity.blogspot.nl/2016/12/redux-comprom...), and a lot of OpenBSD's hardening is in the (simpler) base system, not in GNOME / KDE / Firefox / Chrome / ...
Alternatively, consider not running a full-blown desktop or using Windows, which has grown a lot more secure since the Windows XP pre-SP2 days.