[robto]

Disclaimer: I'm a NixOS user who is interested in switching to Guix but have not actually tried it yet.

Both package managers (Nix and Guix) and the distributions (NixOS and GuixSD) are very young, so expect some missing packages and some rough edges. That said, Guix & co are newer than Nix & co, so expect more missing packages and roughness with Guix. Also, GuixSD being a GNU project, you'll have a harder time finding proprietary stuff packaged up.

Guix is entirely scripted in Guile Scheme, which is a strong point in my mind. And from what I understand, you can drive your whole operating system from emacs, which appeals to me as someone who lives in and loves emacs. It also has a strong emphasis on user Freedom.

But you can use both! This is part of what's so cool about functional systems. I personally started with Nix on Ubuntu, graduated NixOS, and am now starting to look into Guix. And eventually, GuixSD.