Most of the ones out there are weird, anti-configurable systems like mobile phone OS.
The only ones that really seem like "the future" in my eyes are Nix and Guix.
And I'm not going to use those because I already have a good setup with my conventional distro (Debian). Anything less than absolute perfection will not get me to switch.
Nix is imperfect because it uses systemd. Guix is imperfect because it has a smaller selection of packages, and a more difficult configuration system.