Well, I'll agree that until about 2012 I felt that XP was the greated Windows OS in history.
After Win7 got SP1, it became my favorite Windows, and so it has remained. Considerably more stable under load than XP, in my experience anyway.
But the greatest OS in computer history? That covers a LOT of ground...
Assembly running realtime control code in embeded systems....
I never got blue screened with XP. Now I have W7 and get blue screened from time to time. I had thought that went away with W95.