When using an init system with Linux, you are most likely going to be using Systemd. Systemd is what comes with the majority of Linux distros as of current. However, there has been a lot of criticism against Systemd. Luckily, there are other init systems that you can use. I am going to provide some of the alternatives, and you can decide for yourself what you would like to use as a init system.
There is also launchd from Apple. And didn’t Canonical make one in the Unity days?
Canonical’s was Upstart, iirc. No longer maintained.
They dropped support because systemd is superior.
True, but you have to take into consideration that when they made upstart systemd wasn’t a thing.