I think ublue will win over nix in the longrun. Its layered approach to system design seems far more sane. Being able to take a base image and apply gaming patches over it then apply your own personal layer is such a great way for multiple people to build off the same base and not have to resign the wheel everytime.
NixOS is more fun for the user from a tinker point of view but Ublue is better for the distributors and the non tinker end users.