One thing I'd love to know is what the advantages of the different systems are, objectively. I've always used macports, from the very early days, and I just use it because it works, and I know its quirks. I remember brew starting, and thinking "oh, that looks interesting". Yet I never really felt a compelling reason to change.

This article is refreshingly honest about why the author decided to give nix a try, and I very much appreciated that. A large chunk is "it's new and I wanted to try it out", combined with deterministic update times, which I respect. Is there a detailed technical comparison of macports, homebrew and nix anywhere?