Anecdote about the subjective difference between using both:

I've used nix and nixos on and off since the early versions, but it never really clicked with me, and every time I want to write or just read nix expressions I have to reread lots of documentation like I'm starting from scratch again, whereas I would probably still be able to write a debian package from memory alone despite many years of lack of practice. This leave me with the impression that nix has to be a full time job.

In another hand, I gave guix a try recently and was really surprised by how easily all the pieces fell together "naturally".

Also guix being a smaller community, it might counter intuitively be moving faster (due to less care for not breaking things or less bureaucracy, depending on your views). Indeed, another issue I have with nix is how jammed their input queue of PRs is.

I spent a couple weeks casually studying about both, and finally hitched my wagon to Guix. The careful separation of free and non-free software is incredibly refreshing. I appreciate the emphasis on building packages from source. The docs are great and so is the Guile language.

It didn't take me long to get a bootable USB with proprietary drivers and mainline kernel, even though I thought this would be much more difficult.

Nix and Guix are the next generation of package management.

Nix is more idiosyncratic, since Guix usies S-expression syntax.

Also, Guix is free software, with everything that entails.