I’ve been using Fedora for over a year with KDE. Before that it was Kubuntu for a year. The difference is night and day in my opinion. I believe this is due to the constant updates on fedora that fixed many annoying bugs I had with the ubuntu install. The downside is that you are likely to get a kernel update about once a week, it honestly hasn’t been an issue and i’m a college student who needs essentially 100% uptime on my boxes. But in my opinion it’s the perfect trade off since it’s not quite rolling but still on the cutting edge for the most part.

I'm not a fan of DNF as a package manager (it's fast enough for bulk operations but takes a long time to do very simple interactive things, compared to pacman or apt), but I wholeheartedly second this recommendation for people who want to avoid installing hundreds of PPAs and third-party repositories to get their work done. Fedora also has a lot of niche packages (like the Zola static site generator) that are only in the AUR or third-party repositories for other distributions. The defaults are good from a security and usability standpoint as well.

That.

I've been using the KDE spin of Fedora for many years!

If you are willing to switch away from apt, openSUSE is a fantastic KDE distro. It stays close to the base KDE as much as possible (unlike Manjaro).

Whenever i've tried KDE my favorite experience has been on OpenSUSE Tumbleweed. Its a rolling distro, but provides a really nice installer and stable experience because of their automated QA process. The KDE stack is provided as intended by upstream without much customizations (they use their wallpaper for the lock screen and desktop), and the updates are quick. If you try it, you might also like their support for btrfs + snapshots. If an update isn't to your liking, it'll allow you to boot into an old snapshot and rollback.

I still use tumbleweed, but with Gnome and this has been my distro of choice for the past couple of years. (I moved from Ubuntu)

Kubuntu, because I like debs and apt and the appeal of Ubuntu-ish distros is that things generally work out of the box without too much fudging around.

Why does choice of desktop environment impact choice of distro? I ask as a question out of my own ignorance.

I started with arch and I just bolt on whatever desktop environment or window manager I want.

There are occasionally little things that are available on one distribution and not available on others. For example, with Cinnamon and Linux Mint, you can right click on items in the start menu and there will be an option listed to uninstall the clicked program. This was (and probably still is) missing from Cinnamon in Debian / Fedora.

I imagine there are other things like this with most distributions.

Or for something like Plasma, you can go with Kubuntu or KDE Neon. Both of them are Ubuntu derivatives which are meant to be used with Plasma. But KDE Neon will get you the latest Plasma version, and Kubuntu will not be bleeding edge.

I like to get a comfy "out of the box" experience, which can differ quite a bit between distros, especially how smoothly it all fits together.

KDE has their own plasma distribution, I've never used it but it seems like a solid option

To elaborate on this, we (we as in other developers in KDE, not me personally) have created KDE Neon (https://neon.kde.org/) which is Ubuntu LTS + the latest KDE software. It's great for using the up-to-date KDE Plasma & application versions while having a stable base in Ubuntu LTS.

I've personally used it for nearly 3 years now, and never had any problems with KDE Neon. It probably isn't a good option if you'd like to have the newest versions everywhere, since the base system is only thoroughly upgraded on every Ubuntu LTS release.

If you have any questions regarding KDE software or KDE Neon, I'd be happy to answer them on #kde:kde.org (Matrix) which is also bridged to #kde on freenode.

I've been a happy KDE Neon user on my secondary desktop, an Intel NUC, for about 3-4 years now. I use it multiple hours each day and it's been a very pleasant experience, as in it does its thing and doesn't get in my way.

Was seriously considering using it for my primary desktop, but that'll have to wait until there's a viable RDP alternative.

Slackware. I use the Plasma5 packages maintained by Eric Hameleers, and it's a wonderful experience.

Arch Linux because of simplicity

Mageia could be an option.

arch

Another arch-er here.

The main reason I moved to arch was KDE Plasma 5. When it first came out version 5, was buggy, but usable enough to be a daily driver. A rolling release made it easy to get the latest updates and I haven't needed to revisit my decision since the last 5 years.