I prefer Linux, though I've had to use Windows for several things, so in order of the best OSes:
1. Almost anything Linux.
2. Windows, especially the versions 3.11, 95, 98, XP, 7, and 8.1.
3. Every other operating system that has ever been made.
...
100. All Mac OS versions.
Yes, I am quite biased.
@TomRannd The next iPhone will have 200 cameras on the back of it, 20 on the front, and 50 all along the sides. Why? ...Erm, I dunno. 10,000 degree photo captures? :P
Definitely macOS 10.13, but installed on my laptop. Older versions have less features, newer versions have less features, and the official hardware sucks ass (and your wallet).