The nixos module and their tests make it very discoverable how to run many services. Where in arch I actually have to read where programs put there configuration, in NixOS I can already start configuring. Also github search is very value just put the nixos option + lang:nix and you find tons of examples.
It's not that bad if you just want to use/configure existing software - I often find exactly what I'm looking for by googling "[software i want to use] nixos". It gets harder when you start to write your own derivations.
I maintain multiple packages on the AUR and PKGBUILDs are pretty easy to understand imo. I only had a look at one or two Nix package builds and they seemed much more complex to me.
