Linux

KDE Plasma is one of the easiest desktops to use for a user coming from Windows, that's for sure.

Gnome also has its place. I've used it for a few years (up to the Plasma 6 release, where I fully switched to Plasma on Wayland) and I like Gnome in general, its UI is a "modern" mix of the MacOS desktop and a mobile phone UI, whereas Plasma goes the traditional (one might also say boring) Windows desktop look&feel route (although you can also reconfigure Plasma heavily to look and feel however you want, but by default it's very Windows-like).

Main difference, if you set aside the UI, is that KDE Plasma offers a ton of settings and features (available easily via the GUI), while Gnome intentionally doesn't - that means to change some things you need to put in more effort in Gnome (use extensions or change settings via dconf editor, or custom CSS files. and so on).

Then there's the factor of stability - Gnome has always been rock-solid stable for me, while KDE Plasma since 6.x release has been very good but still not rock-solid. I've had maybe around 5-7 plasmashell crashes so far during the whole time of using Plasma. Plasma has a recovery feature for this integrated now, so it isn't as bad, but it's still not rock-solid. The small price you pay for all the great and many features Plasma has is that it's (still) slightly less stable, but due to it being able to self-recover most users probably don't need to worry about it. I've had it on Windows as well - whenever the explorer shell crashes, it instantly restarts. You might have noticed this when suddenly the taskbar and everything is shortly gone but then re-appears. It's kind of the same in Plasma, just that you also get a notification that plasmashell has crashed. I've never had any of this happen in several years of Gnome usage.

However, the Gnome devs are doing some weird decisions... they have very strong opinions about things and tend to not agree to things which they should agree to in order to make interoperability with other software easier. There have been a lot of unnecessary discussions about how to handle client-side window decorations, desktop portals, how to implement cerrtain Wayland extensions and things like that and often there are 2 factions at the end: the way Gnome wants to handle it vs. the way everyone else wants to handle it. I don't like this attitude or selfishness at all from the Gnome project.

But in terms of software and UI quality, I think Gnome definitely has its place. Whether you like its UI or not, is something that every user will see differently. I'd assume that users coming straight from Windows and who maybe also want to continue to use the Windows UI paradigm on Linux will tend to find Gnome a bit alien. That's understandable. Gnome has its own UI paradigm that doesn't try to cater to Windows users. So you need to adapt to it, not the other way around. I also never really care that much about what desktop environment I'm using, because I'm doing so much with Emacs, the terminal and the browser, it almost doesn't matter much what's "around" that. So take my opinion with a grain of salt - I can probably use any UI paradigm and be fine with it. So maybe I'm not the best person to judge how well a UI is done. But I still wanted to give credit and criticisms where they're due.