I want to learn a new backend-language, but can't decide which one.
I already know Go and have basic knowledge of Python and Java.
Which one should I learn?
Doesn't matter what kind of language.

WHY?

try to be master in anyone language.Don't just complete courses.Try to implement project with it.

Java and go are one of the most powerfull language. Python is fav weapon of many developers.

Rust of course! Universally loved by devs all over the world. Delivers the power like C with the ease of use of java.

Node is quite popular these days

Common Lisp

What is your purpose in that? You want to get job using this language? Then look at job listings, check what is popular and pays well. If you don't plan to move, then check in your city. Doesn't really matter what you pick as long as it lands you job easily and pays well.

If you are looking for language to do specific project or project type then it is much harder. Maybe finding language that suits it best is good idea, like for example #F or R if you are into data and science analysis.

@arraysstartat1
I only want to learn it, for doing personal projects at the time, and learn more about programming.

I'd suggest PHP. It's getting better and better and is widely used (in case you were to start looking for a job).

@Jilano or specifically web developer jobs

I would suggest dotnet core if you are an OOP person. Its really great for performance and scaling too!

One word:
Kotlin

Amazing OOP language that just always keeps surprising me with how amazing it is, and it has a lot of focus on the small parts of programming languages that you need to be a pro at the language to really understand and appreciate.

Also, since it's compatible with Java Byte Code, you can import every Java package out there, so you dont have to deal with Kotlin missing crucial packages due to its relatively new status.

Like import-fun said, specialize in one language. I'd recommend java because you are already familiar with it, and because of the moneyz :D

@arcsaber i heard good things about the current php

@host127001 that doesn't count!