DistroWatch Query for nearly all relevant linux distributions without systemd by default.
If you do not know about DistroWatch, I would highly recommend in using it as a future resource for searching for distributions based on specific requirements, and general linux news. They also have reviews which may be of use to you.
Although I cannot personally vouch ...
Artix Linux is an Arch-based distro where its primary distinguishing feature is that, unlike arch, they don't have systemD at all. I don't really know much about it.
From their website:
Artix Linux is a rolling-release distribution, based on Arch Linux.
It uses OpenRC, runit or s6 as init because PID1 must be simple, secure and stable.
Like the other ...
PCLinuxOS defaults to using sysVinit instead of systemD. I don't think they provide any other init systems though... (feel free to edit this answer if I'm wrong)
PCLinuxOS is known for being pretty easy to use and install, though they are based on Linux From Scratch instead of Debian, Fedora, Arch, or Gentoo (most other distros are based on one of those four)...