For me I like iterating on my home lab so it’s nice knowing I 100% did not forget that I left some port open or service running, it’s all nicely defined in a configuration module I set up.

There’s a low chance I’m going to reuse my configs, but it’s nice I have the option.

Probably the biggest value is it’s all written down nicely in a structured and documented system instead of my old sub folders of just/makefiles and bash scripts and’s inlined configuration.

Then there’s also nice stuff: my config also defines a dashboard for checking the status of my services (when I add a new service, it regenerates as the service is added automatically), I can see which users I created to run in containers, i can experiment with a new desktop environment and just comment out a block to go back.

Documented declarative centralized configuration of all my systems; that value can't be overstated.

Then the fact that I can run any version of any nix package from anywhere at any time with a single terminal command,

the ability to effortlessly and cleanly switch desktop environments with completely no friction or fear,

to be able to roll back by booting into any previous configuration still on disk, or entirely rebuild any older configuration I've tracked in git,

Painless and fearless updates with a rolling release, very little chance of borking and I can never get out of step; doesn't matter if I update once an hour or once a year,

I can share my settings with friends e.g. they can try out my MPV config with a single nix command, or consume my flake outputs and add it to their system with merge/overriding changes,

I can clearly version system dependencies for everything that needs them without shipping containers,

I can define development shell environments which is basically like python venvs with requires profiles but for every language,

I can remotely provision a machine, including disk partitioning and luks and initrd ssh, with a single command,

There's a plethora of modules that make setting up complex services with sensible defaults as simple as "enable = true;",

... I could probably go on for a while but yeah

It's about remembering that you did. I have no idea what changes I've made to my ancient Ubuntu box so if an upgrade borks my system again I'm SOL

Also, a Nix upgrade won't break your system, unlike Ubuntu

1. I like having the same system configuration across machines and be sure that everything is the same.

2. I like having all configuration in one place and have comments near the relevant code for extra clarity.

3. Nixos makes setting up root on ZFS a breeze.

4. System as nix configuration makes it very easy to track changes with version control and informative commits.

5. If I fuck up the system I can easily boot into older generation.

6. System can rebuild only if everything (with proper checks) succeeds giving you a greater confidence in things working.

7. System reinstals are quick and easy so on hardware failure you can go back to work very quickly without having go spend days and weeks getting your system so vagualy similar state as before.

8. Nixos made it easy for me to set up mirrored boot so my system will still work fine when one of my boot drives fails.

9. I get to know what is actually installed on my devices and can easily get rid of it.

10. No dependency hell.

11. I can easily try out a program before installing it permanently with nix shell.

12. Impermanence helps me ensure that every folder and file that I need to keep is documented and keeps them in one place for very easy backups and I have 100% confidence at my backups have everything important.

And many other bigger and smaller things that I can't remember right now. I'd honestly be interested in solutions simpler than nix providing the same or greater benefits with more simplicity.

E: Also, because my original comment wasn't well worded I will mention that I meant that once you learn how to work with nixos things become easier and once you get the setup going it's just there continuing to work since the effort is paid in advance and you continue getting the benefits just like that.