I'd say any rolling distro. Try Debian testing or unstable if you prefer Debian distros family (choose KDE during installation). Or try Arch.

KDE also started making its own Arch based distro now: https://kde.org/linux/

But it's one of those immutable flavors. I prefer something more flexible.

I use mint's cinnamon UI on Ubuntu. It's by far my favorite desktop, but yeah Mint's main packages are too far out of date usually.

Fedora

How do you deal with the short lifespan until EOL? I've been using Rocky (and CentOS before that) simply to avoid dealing with EOL so often.

Fedora makes major upgrades pretty easy - you can even do it via the GUI Software Center, then reboot.

Personally I'm using Kinoite[1], an "immutable" version of Fedora that has an immutable base image, which makes it nearly impossible to break things during updates (even major upgrades).

[1] - https://fedoraproject.org/atomic-desktops/kinoite/