This computer has a bit of an interesting history since I initially installed it with Debian via debootstrap, converted it over to Devuan after a short bit (the fork of Debian without systemd), and then successfully switched it back to our favorite standard issue Debian all without having to do a clean install. The server was live and serving away while both switches happened too for that matter!
If you really want a non-systemd distro of GNU/Linux for any reason, it would be best to use operating systems that just don't need systemd anything to run. Even the so-called "systemd-free" distros still need some systemd things these days. GNU/Hurd and BSD comes to mind as free options you can use.