I use .NET because it is one the platforms that has shown a lot of improvement and step ups in the recent years, with .Net Core improvements, being cross platform, extremely fast and going up the benchmark ladder release after release, etc. Also it has been open-sourced and they accept community contributions to shape the future of the framework.
There is also all sort of solutions available in .Net Core for all tastes. Your team likes Functional programming? no problem, use F# and still benefit from all the tooling and cross platform and the Core framework. Want to do Linux? no problem. Want to build mobile apps? use Xamarin and .Net. Want to build web applications with web assembly? use C#. Also sick of Visual Studio for some reason or using Mac? no problem, use Mac and Visual Studio or just go with Cross Platform Visual Studio Code.
Looks like .Net has had a lot of exciting movements in the past few years and I think is the best echo-system for any size software team at the moment.