KDE has sane defaults and looks and feels like Windows UI from the best era. It just works.
There is one app that I installed recently, that used GTK and I noticed it - the ProtonVPN Connect UI, it looks a bit funny, but integrated seamlessly in the whole system (KDE) including the tray icon. It just works. What is the problem?
I used to run complicated setups back in the days, with black/flux/openbox or even enlightenment (16), but now I don't really have the interest or time for tweaking DEs.
GNOME is like a tool that was designed to fit the average user so if you are not the average user (like you know the joke where the average person has 1 testicle) then you have to mold yourself to fit into GNOME (or try to hack it with unsuported extensions that might make it more tolerable) in KDE you have nobs to tweak it to fit you smoothly (like for example with one checkbox I can make the Left Alt to be a Ctrl button so i do not bend my hand and fingers to use my many Ctrl+keys shortcuts).
IMO use GNOME only if you are the typical GNOME user, that prefer to bend themselves over and not to adapt the tool to fit . Avoid KDE if too many options cause you some anxiety or buffer overflow.
Just to give you an opposite perspective...I was a long time Kubuntu / KDE Neon user (almost 10 years) and shifted to Gnome couple of years back (Ubuntu 22.04), now running 24.04. It's been very stable and out of the way. I am not sure why people are complaining about UI, for me it's barely visible on my two screens. All open-source and proprietary apps I use run well and without glitch. It took me an hour to get used to the "Gnome" way when I shifted.
Gnome is more opinionated. There are fewer options overall, the core apps are generally much simpler, and it assumes a specific way of interacting with your computer. You can change this with extensions, but if you are dead set on a specific workflow and need to venture beyond a small set of widely-used and well-supported extensions then it may feel like you're swimming upstream.
I personally prefer Gnome because I don't mind trying out new workflows and it ended up being a good fit. But I understand why many "hacker types" would prefer KDE, and (assuming they've ironed out stability and release scheduling issues) I agree with other comments that KDE would make for a better default experience, especially for people coming from Windows.
Thankfully, both exist and you can try them and see what works for you!
Last time I used KDE as my main desktop was v3.x, I switched away once v4.0 was released (at launch it was slow, unstable, and lacked many features). But it seems KDE 6 is likely to fit my personality more than recent Gnome versions.
I'm now switching back, and will likely go with either Gnome or KDE. I've used XFCE, i3wm, etc. for years before – and briefly tried Sway too before I switched to Mac – but from what I've read it sounds like the "big" DEs make life easier post-Wayland.
Anyone want to share why you currently choose KDE over Gnome?