I'd suggest Linux Mint if you want Ubuntu with a GUI that doesn't suck, though Kubuntu is probably a decent choice (KDE isn't to my taste visually so I don't use it, but it absolutely doesn't suck and many people like it). If you want a rolling release instead because you want to live on the bleeding edge, Arch is hard to beat.

I'd recommend Fedora with Gnome, though KDE is also quite good. You get a stable distro with still recent libraries.

I can second Mint for a good GUI, but if you want Wayland I would probably either go for Pop!OS with the new Cosmic desktop beta or Fedora with KDE over any version of Ubuntu. Snap packages suck still IMO

I should probably mention that Linux Mint disables Snap packages by default (for reasons of principle that boil down to "Snap packages suck"), though you can reenable them with a single command if you actually want Snap. That's another point in Mint's favor for me.

Agreed. Mint leaves the user fully in control by default, and that's always a win in my book.