NixOS finally convinced me to switch, since the declarative config and rollback functionality meant I went from accidentally bricking (or at minimum "mysteriously unstabling") each previous Linux distro I tried at least once a year (NixOS basically gives you built-in safety belts to counter all the untested possible Linux configurations) to being able to mess with configs to my hearts' content with aplomb (since backing out is trivial and can be done in GRUB). It really feels like "Linux, unleashed" and like I've made the "final distro hop." There is a feeling of "Yep, this is it!" I have the same fearless feeling to alter configs that I have in macOS, except with, you know, more open-source and less walled-garden...
Plus, I can finally boot off ZFS and a mirrored boot drive with no worries thanks to an excellently written guide and first-class ZFS support (just pick the latest ZFS-compatible kernel via a special config that automatically does this for you!)
The negative of course is that Nix/NixOS have a learning curve. Once you grok it, though, you will literally want to install it on ALL your machines. It has eliminated so many headaches (assuming you can find the right option to tweak).
