It's a very productive ecosystem. It doesn't have the same level of enterprise factory wartiness that Java does; its Windows IDE is extremely integrated; it lets you write functional-ish code in an imperative environment; and it has LINQ, which is fantastic.

Having cut my teeth on C++ and being reasonably familiar with Python, I'll choose C# for anything larger than a script that doesn't need direct memory layout control.

Deployment story is still a bit of a pain sometimes.