What's a good live distro for a well-integrated KDE experience? I haven't used it for years but want to see how it is these days. I used to love the way the core-ish apps seemed to work together in concert.
I wouldn't recommend Kubuntu or KDE Neon, as the latest KDE releases are developed on the latest kernel, so, using it on Ubuntu based distros with old kernel and old packages might not be the best experience for the latest KDE releases or even cause issues.
Anecdotally, KDE also runs better on Tumbleweed than on Fedora for me.
Also, maybe give Gecko Linux a try, it's a sane, noob friendly, batteries included version of Tumbleweed, with Nvidia drivers and proprietary codecs out of the box, along with a default to X11 because the author doesn't consider Wayland ready for prime time. Just make sure to do a sudo zypper dup after installation to update the OS and packages since the packages on the ISOs are out of date as the ISOs are updated about twice a year, which is not ideal for a rolling distro but to be fair, the whole Gecko "operation" is run for free by one guy so this is understandable.
I use openSUSE Tumbleweed where KDE is up to date and well integrated (I really recommend Tumbleweed for a good KDE experience), I see that they have a live image they call JeOS ("We also have JeOS, Live images. Check out Alternative Downloads!") [2], I haven't tried the live image but it's probably very good.
1. It's Ubuntu based, so comes with snap. Not a fan. 2. It's LTS based, and tends to update not on schedule but with about a half year delay. That means packages get old... 3. (I lied!) It's both bad and good: updates are, even on the user branch, too damn frequent :)
I would recommend against using KDE Neon daily though. Or Ubuntu by the way. It used to be a really good distro, but it's not so much today I think.
Fedora's not been great, upgrades always bring some kind of changes. In 35, I ended up with broken system monitoring applets. Still better than in 34, where, in addition to broken monitoring, Plasma needed to be restarted 3 times before panel drawers unbroke.
Never managed to get night mode not get immediately overridden by some other part of the OS.
Rolling releases hugging upstream very closely may have breakage, but that isn't KDE specific. It is the reason I went back to Debian stable, because it is indeed stable. The breakage I had with Opensuse and Fedora was Wayland related as far as I could establish.
I'm on Debian now, which ships an older KDE, but, everything works, which is a first.
(That was separate from the other couple of times when some python packages required manual intervention to not yield a broken upgrade but that may have been related to AUR. Not a biggie for me but probably caused frustration for many users)
Perhaps one of reasons why it worked this reliably for me is I turnt composition off (there is a handy hotkey for that in KDE) but it worked nice with it enabled as well. I only switched it off because I never managed to invent a reason for it to be enabled.