The well-supported thing is in great part only thanks to Debian. And about the desktop, cmon, it’s just Gnome with built in extensions. No issue with that and totally valid to enjoy it, but it’s certainly not “lightyears” ahead of anything.
But if your experience with Ubuntu is good, then great, I’m happy that you enjoy the Linux ecosystem, and I truly believe the best distro is the one that fits best for your personal needs, and if Ubuntu does that, then it’s great 😁
That’s a great advantage of Ubuntu, and they surely brought alot to the table when it comes to desktop Linux in its early days. But it just happens that Ubuntu forks also tend to take that benefit too (like Mint, Zorin or Pop) while also giving to the newer users what is, to me, a more standard Linux experience that follows current trends, like the adoption of Flatpaks over the weird push for Snaps on desktop that Ubuntu has, or actual functioning app stores instead of the rather polemical App Center that almost released without a .deb support recently. That’s why I tend to recommend friends to use Mint or Fedora