I've used runit, openrc, briefly upstart (what a trashfire that was), and I don't miss a single thing about them while writing systemd unit files.
I've used GNU Shepherd on Guix, and honestly, meh, systemd feels way more pragmatic.
I've also used systemd-networkd as well as NetworkManager, and feel like they both still have a few warts, but overall prefer systemd-networked on servers.
I've used grub, refit, and systemd-boot, and gotta say systemd-boot is my preference there too.
I haven't really used systemd portable services, but I've used docker and don't like it, and my overall impression is I'll probably like portable services more.
Are there other alternatives I have to use before I'm allowed to have an opinion? What alternatives have you used which made you feel so enlightened?