In some ways X11 with it's focus follows mouse, don't raise on focus, select:middle click paste features provide a far more refined desktop experience then mac or windows ever could. No wait, stop laughing, sure X11 was a garbage fire when it came to consistent professional design, but because it was such a wild west of an environment there was place for real ui innovation. I know, I get grumpy fast without middle click paste. And I hate having to raise a window in order to click and type on it(A common access pattern for me is to read docs on the top window while I am operating the bottom window).

Yes Aqua was quite striking. Also much more consistent than the rag bag of different styling you see on Windows or Mac today.

Even before those, AfterStep, Enlightenment and many others were really nice.

Regarding Amiga screenshots, they've taken care to get the DigiPaint aspect ratios right, but the Workbench 2.04 screenshot is in a resolution that comes from an add-in graphics card rather than the Amiga's custom chips. It's a resolution Workbench wasn't graphically designed for, so it looked wrong in such a resolution at the time. If you double the screenshot's height, then everything (text, icons, window gadgets etc) looks right.

It would be more representative of the OS, and the era, to have a height-doubled "HiRes" screenshot, 640x200 or 640x256.