Having used both on a regular basis, I hope they stick with GNOME. KDE is highly-configurable, which brings about a level of fun, but otherwise somewhat unpolished and at least a bit more buggy.
Nate Graham championed community goals such as "usability and productivity", "consistency", while also focusing developers on high-priority bugs and blogging weekly about the progress: https://pointieststick.com/category/this-week-in-kde/
On KDE you can also use extensions which are equally wonky, but KDE offers so much more out of the box options that I find myself needing far fewer extensions.
Also, KDE is much quicker on implementing stuff like VRR or HDR support which Gnome is still lacking. But at the same time, KDEs implementation is still lacking in some areas. While I personally like the "move (relatively) fast and deliver early results" mentality, being on a semi rolling release like Fedora I'm not stuck with the broken state for very long. In that sense, I can understand why people may be annoyed with partially implemented features when they're stuck with them for a long version lifecycle.
On my desktop I use sway, coming from i3, and it is mostly working OK. Every time I tried Gnome and Wayland I had ocean of issues and after couple of days reverted to Gnome with X.
KDE recently switched everyone on Arch to Wayland (the new default), making it my first brush with Wayland, and maaan... I'm impressed with how performant Wayland is (it's as smooth with composition and no screen tearing as X11 is without composition and with screen tearing -- and the key input latency is palpably less than in X11), but there's been one little problem: total system freezes periodically. Mouse, keyboard, sound, everything. A totalitarian kind of freeze -- the kind only possible with Wayland's design. :p And the periods were once every day. Then, after a few days, twice every day. Then once every 15 minutes! Then once every 5 minutes!! As I tried to look up how to switch it back to X11, as though angry with me and wanting to stop me, it started crashing faster!!! (I figured out it was the little gear icon at the sign-in screen that allows you to switch KDE back to X11.)
So I'm sticking with X11 for now. :p I'm also exploring WMs like dwm and OpenBox to see if I can have something leaner that won't threaten to kick me off of X11 anytime soon.
With both KDE and Sway I use different scaling on each monitor and it smooth and perfect.
You mean Arch recently switched its KDE users to Wayland.
KDE has no say on what Arch's defaults are. That's what distros are for.