NixOS. Having a config-defined system is a bit too different at first, but really nice when it comes to system reproducibility, and being able to roll back.

It made maintaining my laptop + workstations the "same" a breeze, although it took a bit to learn and settle into something that works for me. It seems today things are easier for newcomers, but Nix Flakes are still "experimental", and thus the documentation on things might seem confusing or misleading sometimes.