Well, uBlue can be as light as you want it to be.
Some other projects I’m thinking of:
- VanillaOS (Debian based)
- NixOS
- Fedora CoreOS
- uCore (based on CoreOS)
- openSUSE MicroOS
- EndlessOS (Debian based)
- blendOS
Is it for a personal computer or a server?
Maybe try the Atomic version of Fedora Budgie? With my limited testing it looks like a really easy and (almost) unbreakable distro.
Otherwise uBlue has allot of images, you can make your own even.