Agreed, KDE is great. I like Kubuntu and KDE Neon. A little bit frustrated when I have to use a Gtk application; it's sometimes not working well in a KDE environment.
I use Windows/MacOS/Linux(Ubuntu) on a regular base.
As a ordinary end user, I feel
1. Windows software are usually good at product function design.
2. Mac has a better enforcement on overall UX. The visual across different software (from different vendors) are much consistent.
3. Linux desktop is unfortunately still missing above 2 points.
Some Linux distro provides really good visual, but it only applies to its built–in programs. If you'd like to switch to the external programs, the system visual might be fragmented.
I really hope in this new wave people could make some consensus on the visual of Linux desktop.
This is exactly the number 1 challenge for Linux Desktops: hard to coordinate with each party, then we end up hundreds of different distros.