I also like SliTaz: http://slitaz.org/en, and Slax too: https://www.slax.org/
Oh and puppy Linux, which I could never get into but was good for live CDs: https://puppylinux-woof-ce.github.io/
And there's also Alpine too.
thank you for this reminder! I had completely forgotten about SliTaz, looks like I need to check it out again!