We are using Windows Server 2016 for our organization's backend applications which reside in a data center. HP provides us with our Windows platforms, and we also have Unix platforms from them as well.
We have been using Windows environments since I joined my organization, which is close to 20 years now. Currently, we're doing what you can call a hosted private cloud with colocation and we are running some huge workloads using Windows Server in this cloud.
From our side, the organization's 2800 end users are mostly running Windows 10 in a highly virtualized environment. So whenever we need more resources, it takes just a couple of minutes to get it up and running.