OpenSUSE Tumbleweed is pretty solid and 98% of the refinement of Fedora, that in my opinion, it is the most polished of them all. Now, using Fedora supports companies like Red Hat/IBM so it is a no-no for me.

The only thing OpenSUSE has is that is independent so does a few things differently than Debian or Fedora based ones, but after a few retouches that you will learn in no time you will be at the level of Fedora. It is perfectly OK for beginners, just that there are a few things differently, sometimes for the better like many utilities from YAST, but will be different from what you find in most non OpenSUSE forums. Again, is minimal, 95% of the staff is the same. Unfortunately, it does not have the costumer base that Ubuntus/Mint/Fedora has, but the supporters are technically highly committed and competent, they just need to improve in their marketing arena that is what is holding them down.

Another KDE that I like is TuxedoOS. It works perfectly in non Tuxedo devices and very stable in my experience... I even had better stability experience than Kubuntu, and that says a lot.

Did not play enough with Manjaro and will try in a few days. It had some bad press but I think is more due to diverging a bit from Arch philosophy of instant updates than anything else. CachyOS I recommend only for latest computers or those willing to adjust things a bit once in a while.

For older devices, MXLinux KDE is the ideal in integrated graphics chips.