C# is the peak of all programming languages ever made. all other languages are completely irrelevant in its powerful presence. C# isn't just an improvement on Java; its an improvement on every programming language. there is nothing out there that has more features or functionality than C#. need to root around and change the program's compiled data on runtime? reflection. need to read through a massive list and sort it alphabetically, numerically, by value, by date of birth, and remove any entries that are green? LINQ. C# also has null conditional and coalescent operators so you can keep your entire program safe from null values without having to write conditionals everywhere to check for them.
this
but in reality C# is barely used anywhere in industry, so it's a useless skill
(actually, unity game devs use it quite a lot nvm)
Javascript, unironically. It's easy to learn and do things with it right off the bat, and it has presence on essentially every platform. And with tools like Electron and Apache Cordova, it's possible to build native apps for every major platform.
the problem with learning javascript first is that it actually gives you terminal stage brainworms and bad habits that you will do for the rest of your life