At this point almost all major package managers try to not introduce any non-reproducibility, so it comes down to package itself building deterministically. Nix

At this point almost all major package managers try to not introduce any non-reproducibility, so it comes down to package itself building deterministically. Nix just have an architectural sandboxing and isolation that enforces is maybe a bit better. But the moment e.g. ArchLinux devs fix determinism and upstream it in certain package, it will become deterministic in NixOS and others, and vice versa, so there is not going to be a lot of differences between distros at this point. Everyone agrees that deterministic builds are a good thing.