Just checked: According to `check-dfsg-status`, I have exactly one package from non-free-firmware, a wifi firmware package, and one package from contrib, anbox (I don't remember, why I have it, so I remove it now). Everything else is #Debian main. Maybe that's an extraordinary simple setup?
I recommend Debian stable to most users, and I myself use stable at work. It's so great to have at least two years without having to deal with new software, but just get things done 🙂