why openbsd over freebsd? (i've not yet used either)

openbsd is developed at a much slower pace (much more carefully) than openbsd and makes much fewer compromises in terms of what they accept into the base system (no microsoft NDIS wifi drivers, few driver blobs, no nvidia, no wine, no emulation, etc.)

it’s about the only secure operating system available

freebsd isn’t bad, and it’s a lot more usable as a desktop OS