XFCE is great but OSTree really is the future. I don't see any reason for still using the dinosaur Ubuntu in a world where one can have Fedora Silverblue.
OSTree: https://ostree.readthedocs.io/en/latest/manual/introduction/ -> The underlying architecture might be summarized as "git for operating system binaries"
vs
XFCE: https://www.xfce.org/ -> Xfce is a lightweight desktop environment for UNIX-like operating systems. It aims to be fast and low on system resources, while still being visually appealing and user friendly.
Also that Silverblue thing, assuming it's this site: https://silverblue.fedoraproject.org/ doesn't really do a good job at explaining what it is...
(I largely agree that OSTree-based systems are better, but Ubuntu is so popular that it is unlikely that Silverblue replaces it soon. By the way, Silverblue fans should look at Nix ;).)
Ubuntu has the full force of upstream Debian behind it, while Centos/Fedora has Red Hat upstream, which just got bought by Oracle. Is anyone in the Centos/Fedora ecosystem concerned about the sale? What happens if management simply quits making public RH streams available? What if the lawyers come out as usual?