I love NixOS. I'm going to start running all my machines as NixOS. I was running a mix of Arch Linux and Ubuntu. The declarative configuration along with the great package availability is fantastic! I also really appreciate the documentation which is scattered but often very good. Documentation such as the OpenZFS install documentation is great for getting a mirrored setup running to protect a server from a disk going bad. https://openzfs.github.io/openzfs-docs/Getting%20Started/NixOS/index.html#root-on-zfs