Anyone able to point me towards some good resources/arguments for or against installing packages in X, Y, Z ways? My end-game is a building a set of expressions I can throw to NixOS to build my ideal system. Still pretty new to Nix & NixOS, but the options I see are:
* `nix-env`, the imperative approach, which I've been avoiding
* `environment.systemPackages`, packages get installed for all users and updated on rebuild
* `users.users.<name?>.packages`, packages available for only one user, I think?

I'm mostly wondering if there's pros/cons to `nix-env` vs the declarative approach that I'm not yet aware of.