Given GP's question, they're likely not someone who would spontaneously whip up an openbsd router. Maybe they don't care to fiddle with a command line, read up

Given GP's question, they're likely not someone who would spontaneously whip up an openbsd router. Maybe they don't care to fiddle with a command line, read up on dhcp servers, ipv6 router advertisements, pf configuration and what have you. In such a case, throwing opnsense on some machine, clicking around on three pages and calling it a day isn't that bad. The experience is close enough to an off-the-shelf router (except for the installation part), all the while getting a much better security situation.