Before Nadella, Windows wasn't nearly as user-hostile as it is now. There was no mandatory telemetry, there were no forced updates, end users weren't treated as betatesters and QA wasn't non-existent. And now they are taking away the ability to use Windows without Microsoft Account.
Of course there are also many other problems with Windows 10, like the UWP fiasco, but they're minor in comparison to what Microsoft is doing with user's freedom and privacy.
I always preferred Windows to Unixes, but at this point I think it's time to give up and switch to some Linux distribution. It's clear that the situation will only get worse.