I stand by that OS X Maverick was the most beautiful of all the macOS releases.
Actually that OS in general is what convinced me to buy a mac in like 2014; it felt like nearly every criticism I had with macOS at the time had been addressed. I miss those days.
I thought Maverick reduced the skeuomorphism, I was glad to see it removed. Apple had got to a point where shadows and reflections weren't consistent between icons and windows and the Dock. Briefly, Microsoft lead good design with Metro and the flat, minimal background noise.
https://en.wikipedia.org/wiki/Metro_(design_language)
https://www.macworld.com/article/222218/get-to-know-os-x-mav...