If your application doesn't have special requirements (e.g. heavy computations, graphics, etc..) then using C# + WPF (or Winforms) is very efficient in the sens

If your application doesn't have special requirements (e.g. heavy computations, graphics, etc..) then using C# + WPF (or Winforms) is very efficient in the sense that you can get a lot done quickly. Visual Studio is a great IDE, MSDN documentation is not bad, and because a lot of people use those technologies then whenever you hit an issue it's pretty quick to find someone who had the same one and solved it (e.g. on StackOverflow).