Strong typing is admittedly great and there are solutions to introduce that in JavaScript. However, this is hardly a dealbreaker in complex apps written in JavaScript.

OOP, interfaces: debatable and unnecessary fluff. There are plenty of productive languages without OOP. Example: Elixir. And there are plenty of productive languages without interfaces. Example: Go.

Reflection is unnecessary in JavaScript. You can access any property within an object dynamically and the language is interpreted, so there's no need to perform fancy reflection operations at runtime.

Dependency injection is an engineering pattern. You can apply this to almost any language. And ironically, plenty of JavaScript backend and frontend frameworks have attempted to use it successfully: Angular, Ember. Hell I even wrote my own DI layer once upon a time. https://github.com/divmgl/nwire

I'm sorry, I really disagree with you. I believe C# has the ability to be productive, but there is just no way you're going to convince me that it's superior to JavaScript and its ecosystem. There's a lot of disdain on Hacker News for JavaScript and it's honestly beyond me.