I prefer windows 7.
It might not have the elegant look like windows 8.1 and windows 10, but it's really decent. Also, I could choose from so many anime themes. I don't have to worry about a roundabout to install anime theme in my laptop, if I use windows 7. Of course, the modern laptops are not supporting windows 7 anymore, because of the change in architecture.
I dread the day, when I have to abandon my current(Second) laptop. I don't want to part with windows 7. That's how much I like the version.