Which application is best for coding on Microsoft store?

Answer 1

C# is the flagship language for Windows at the moment. Using Xamarin and similar interfaces, C# is in my opinion a good language to have. Another option is C++

Answer 2

I don't get it. Why do you want to code on Windows Store.

Answer 3

Of cource crossplatforming C#

Answer 4

Jake The Great Why not? It's a great way to reach out to casual pc users.
I'd recommend Visual Studio and C# or C++, though keep in mind that universal apps have a number of seemingly arbitrary limitations. Read the documentation carefully if you run into issues.