My interest in the init system question started when I began enduring the consequences of the switch of Linux to systemd and, after using Devuan for some time, I ended up using Void Linux.
Void uses runit, which is very simple (< 500 LOC vs. 2.5+ MLOC for systemd), yet very efficient as an init and supervision system.
Its author(s?) have brilliantly demonstrated their command of the KISS principle!
I've also tried Devuan 3.0, which now offers the choice between SysV init and OpenRC. OpenRC is admittedly smaller than systemd and strictly focused on system initialization, but it internally relies on SysV init. Devuan with OpenRC appears to be noticeably slower than Void at boot (less noticeably after boot). I haven't compared with a pure SysV init Devuan 3.0, but I have used Devuan 1.0 and 2.0 (both SysV init only) previously and don't remember they were so slow to boot.
Last year, I have tested GhostBSD and besides its high memory usage, I have been impressed by its slowness. It also uses OpenRC instead of BSD RC, but GhostBSD is slow even after boot, so I hadn't put the blame on OpenRC at that time.
I've recently tested Artix Linux, an Arch-derivative offered in 3 init flavors, OpenRC, runit and s6. I tried them all and came to the same conclusion as with Devuan: OpenRC is noticeably slow - and much slower than runit. s6 didn't demonstrate any blatant superiority over the others, so I didn't investigate any further.
What I like with simple pieces of software such as runit is that the less lines of code, the less bugs/security holes and the quicker the fixes. And the easier the learning for admins and contributors, of course.
Like other participants, I think FreeBSD doesn't need to change its init system, it is simple enough and does its job well. If some more improvements can be brought (parallel start has been cited), that's fine, but for now, development resources would be much better employed in other areas.