I think it's somewhat unfair to use number of packages vs Nix as an argument against Guix. Nixpkgs has the biggest package repository of all the distributions,

I think it's somewhat unfair to use number of packages vs Nix as an argument against Guix. Nixpkgs has the biggest package repository of all the distributions, and a much larger community. If you compare Guix against Arch for example, Guix comes out more favorably (15k packages) vs Arch's 12k. Guix packages tend to be very well integrated too, usually running upstream test suites, leading to fewer run-time problems. I think only Debian and Fedora matches Guix on this practice.