At some point (after years!) it became OK and I went back to it, but it was never as good as KDE 3.5 was for me. I realized it was not just nostalgia, when a friend showed me a laptop with KDE 3.5 and used it for some minutes.

While the whole DE got worse, there's two pieces that got better and better, Kate and KWin.

And desktop applets. KDE 4 is the only environment I ever used where these were stable and reliable.

> stable and reliable

They were not, for a few years.

They were for me, even on 4.0. Nothing else worked, but the plasma widgets did.

KDE 4 is not updated any more, is it? I switched to KDE 5 well over a year ago, and found it better already back then. It's very solid these days I think.

In fact KDE (Plasma) 5.8 will be an LTR. https://www.kde.org/announcements/plasma-5.7.95.php

KDE 4 was pretty decent by the time they abandoned it in favour of the still-immature KDE 5 (or Plasma 5 or whatever they're calling it now). The CADT approach to software development is really annoying.

"Best" in everything? or best in specific aspects? Have you tried Pantheon? (elementary OS)

That can be customized a lot (instead of the Gnome mindset of "Do on my way or fuck your self"), and run fast even without 2d/3d acceleration (aka the old good X11 SVGA driver ) ?

PD: Add that anything based on Qt can handle faulty graphics drivers far better that Gtk3.

And KDE 4 wasn't realized exactly with the mindset you describe with so much candor? Now Plasma 5 can be more flexible, sure. But when you don't give users a usable alternative for years people tend to look for alternatives.