Lack of customization which leads to dogshit workflows. I feel like I'm wading through 3ft of shit whenever I use Windows. And outside of installing some 3rd party applications there isn't any way to fix it. Every major Linux DE runs circles around Windows DE in terms of customization and workflows.
Telemetry data and ads in the OS is another reason for anyone that cares about their data and privacy.
Lack of control. Change settings to maybe fix some of these issues and Microsoft comes along with an update and reverts your changes.

I choose Linux because it offers privacy, customization, and control over my computer. The biggest epiphany I had when I switched to Linux was feeling like my computer actually belonged to me again.