For me, I was enamored with the simplicity of it. You click Start and the Start menu just appears, without having to spend 10 seconds connecting to the internet to refresh a bunch of tiles that I never wanted in the first place. There wasn't any half-baked "assistant" trying to suggest new spyware for me to install. It didn't try making me sign into a Microsoft account just to open the photo gallery. The only "bloatware" it came preinstalled with was Outlook Express. The whole experience just made the computer feel like a tool to use for a purpose again.
It's funny, because I remember thinking when Vista and subsequent versions of Windows came out, that it was amazing we ever survived with something as primitive as XP. But these days, all I want is to go back to that.