Back in the 90s, we were shown the projections of what Unix/Linux and Windows would be capable of over time and each year, the gap between the power of Linux and Windows widened. Generally, because Linux is more efficient, given a little bit of extra CPU or memory, Unix/Linux could do more.
Also, in the 90s, Unix/Linux was C2 secure out of the box, as was Windows, until you plugged it into a network. (Genuine fact, not a joke).
By the 2000s, Windows had been good, stable enough, and secure enough for hosting applications.
Windows is more expensive because you need to purchase one license per machine, and you need to give it a little more CPU and Memory than you would a Linux box.
I've not seen any objective evidence that the OS itself is unstable when configured correctly.
It really comes down to whether you need a Windows machine or a Linux machine to run your environment.
I've recently worked for an Enterprise whose Windows code had been rewritten from .Net Framework to .Net Core, got containerised and ran Kubernetes/docker pods on Ubuntu nodes, which significantly outperformed the .net Framework code which had to run on Windows nodes.
When Microsoft themselves run their SQL Server services on Linux in Azure, I'm questioning whether Windows rather than Azure will be a platform in the future.
It still remains the business desktop operating system due to the ease of locking it down.
Yet, as a Unix/Cloud person. I just wish that Unix/Linux would give me the flexibility of the NTFS filesystem. (although you can keep the fragmentation)