I've given both the package managers a shot with home-manager and Guix home running on Ubunutu. I enjoyed guix a lot, but because it's so focused on building from source installing software took a very long time. Maybe my setup wasn't right, but it would often take several minutes to install a package because it had to compile a bunch of dependencies. I've since moved back to Nix for the day to day, but I may try guix again at some point.