From what I can tell (I've only used NixOS/Nix), Guix has considerably more thought put into the UX: Nix is currently undergoing a transition to a newer CLI; Nix's nomenclature is confusing; Guix has much better documentation; Guix has its equivalent of Nix's home-manager built-in.
There is still some division in the Nix ecosystem between the pre-flake and the experimental post-flake way of doing things.
Guix uses an established programming language for configuration, which some might find attractive (I actually quite like Nixlang after getting used to it).
Guix makes installing non-free software a hassle (you have to include community sources). Nixpkgs doesn't impose this restriction, though you still have to explicitly allow the install of non-free packages when running Nix.
Overall, Guix seems like the more polished product, though NixOS/Nix is similar in functionality and has a larger collection of packages and more traction in general.
> Overall, Guix seems like the more polished product
Possibly when comparing the Guix vs. Nix package managers, but for Linux distributions GuixSD ("Guix System" now) is very far behind NixOS in this regard. I've tried to install GuixSD on different hardware several times over the past couple years, and failed every time, between a lack of drivers and unpolished or buggy installer. Last time the installer wiped out my partition table without prompting when I went in to manually partition (to set up dual boot).
NixOS on the other hand has always been flawless to install, and now there's even a modern GUI installer.
I like Guix better in theory, but Nix wins in practicality.
Well the thing with the "Guix System" is that is uses the LinuxLibre kernel. So if the hardware you have requires proprietary bits or driver, it just isn't included. That isn't to defend Guix in anyway, but the problem doesn't seem to be Guix when you read the fine print of the distro, the problem is your hardware.
So, do I agree necessarily agree with GNU's official distributions having this philosophy? Not really. Firmware and drivers is probably the one area I think the GNU people should finally throw in the towel. It keeps people out of running it, or doing so with relative ease. And the battle is for the most part lost on that end. But they do essentially tell you that it is likely it won't work across a lot of hardware out of the box.
"Linux, the kernel developed and distributed by Linus Torvalds et al, contains non-Free Software, i.e., software that does not respect your essential freedoms, and it induces you to install additional non-Free Software that it doesn't contain. Even after allegedly moving all firmware to a separate project as of release 4.14, Linux so-called "sources" published by Mr Torvalds still contain non-Free firmware disguised as source code.
Stux, a cute penguin. Few realize he's not Free
GNU Linux-libre is a project to maintain and publish 100% Free distributions of Linux, suitable for use in Free System Distributions, removing software that is included without source code, with obfuscated or obscured source code, under non-Free Software licenses, that do not permit you to change the software so that it does what you wish, and that induces or requires you to install additional pieces of non-Free Software."
I think that allow unfree in nix is practically the same as adding nonguix repo to your channels. Both are essentially one line of config in some file.
There is still some division in the Nix ecosystem between the pre-flake and the experimental post-flake way of doing things.
Guix uses an established programming language for configuration, which some might find attractive (I actually quite like Nixlang after getting used to it).
Guix makes installing non-free software a hassle (you have to include community sources). Nixpkgs doesn't impose this restriction, though you still have to explicitly allow the install of non-free packages when running Nix.
Overall, Guix seems like the more polished product, though NixOS/Nix is similar in functionality and has a larger collection of packages and more traction in general.