Appimages don’t really “install”, you have to use a different program to create start menu shortcuts and such

Flatpaks are fine, i like the sandboxing approach. It can cause some issues in my experience, discord probably being notorious for the IPC being dysfunctional for years.

Nix is good if you’re using NixOS or home manager. It’s also good if there’s a command line utility you only want to use once as you can just run

nix run nixpkgs#<program> or whatever

dnf is fine. No complaints.