Linux

Just use Fedora. It's very up to date and it's upgrades are flawless.

My record is 15 upgrades (before getting a new system). It's even been fine through Intel -> AMD CPU swaps.

I would recommend void, alpine (kde plasma auto installer may still be broken for some users, works for me tho, also musl so if you need appimages or some very specific applications don't use it.), alpaquita (much stable alpine with glibc if you need appimages), slackware (current only, it is stable rolling, and their point release features very old kernel and packages so I wouldn't recommend it, paldo (stable rolling, gnome by default but plasma installable.), gentoo (if you have time to compile, why not it as stable as rolling can get without it being openSUSE), openSUSE (easiest rpm based (Oracle fork) but still IBM code nonetheless)

Gentoo.

It's rolling release, has stable and testing packages, and users can choose between them per-package (or globally) and it runs or is easily made to run on pretty much everything.

Psst... Try nixos 😹

debian (mx-linux has a kde version if you want less hasle then pure debian) or opensuse leap on the "stable" side, opensuse tumbleweed if you want more recent packages (i've never had it destroy itself like arch, its been very stable for a rolling distro)

An immutable distro with a heavily customized KDE desktop is Nitrux. Check it out at nxos.org

• Siduction
• openSUSE

Omg you just described slackware. Join us!

Same recommendation as usual from me :) pepparmint OS , Debian base extra on top

Solus. Snaps optional.

Slackware current.

Seems that Slackware is what you are looking for.