Scalable products. Usually, business needs are growing and your software has to scale with it. .NET provides a scalable environment and allows for redesigning ongoing applications in order to match the growing needs of the business.
Cross-platform needs. In case you need an app that works across platforms, .NET will be a great choice as most platforms are covered and you can reduce development effort while expanding your desktop or mobile app to other operating systems. Also, .NET can be used for such specific engineering cases as gaming (including Xbox) and AR development (including HoloLens).
Enterprise-scale infrastructures. It’s still a debatable point whether .NET is designed mostly for enterprise use. But Microsoft makes sure it provides the widest toolset possible to build and cross-integrate enterprise products, both internal and public ones. It also supports a robust enterprise mobility ecosystem.