Yes, so.....win98/win2000 interface. I don't have any idea why you'd look at the attrocity that is win 11 and say it's "beautiful". It's not. It's mostly just empty coloured boxes that don't have any inherent meaning.
A lot of this is simply because the newer designs are based on large screens while Win98/2000 was hampered by the requirement to being readable at 800x600 and 256 colors. Using gradients, negative space and was a luxury not afforded in 2000 but it does help.
I honestly hate how it looks and I think it is fucking ugly.
Yet I still defaulted to switching back to it (back when that was simple, don't think it's an option in win 10 anymore) just because the new one was so anti-functional. It was that bad.
I wouldn't be surprised if many users did once they knew that it was even an option.
Peak of "traditional" while still looking decent was honestly XFCE for me. Since then I went full geek and set up i3 tiling manager with basically workspace/screen per app, as I realized near-everything I do is just "running 2 full screen apps on 2 screens" so I optimized for that.
I just find the look ugly. There is no objectivism in preference to how something looks.
Ugly would be, with no arguing, the first editions of Amiga OS. Look:
http://toastytech.com/guis/amiga1.html
http://toastytech.com/guis/amiga2.html
Windows 95, being designed for 256 colors, looks really fine. Ok, Mac's System 7 it's prettier, without any doubt, but as I said the Amiga OS 1/2.x versions are far worse.
Windows 95 it's boring in the sense of being tied to a corporation based style, with cubicles.
I have fond memories of using wxpx64 which was basically w2k3 desktop edition.