None of them, as long as you haven’t outlined the project you’re going to work on.
Python is everywhere.
Java is everywhere.
NodeJS is in many places too.
Many big firms and companies use them, DropBox has many millions of lines of code in Python. Applications such as Instagram, Pinterest, Quora, and YouTube are users of Python.
Google uses Java a lot, like a lot. Have a look at their Github repo, they're deep into Java and C++.
Many companies also use NodeJS. Netflix is one of them, as well as many others.
Remember, none of these companies use only one language: they use many languages, each for different purposes.
Languages should be used for the right purpose. You need to use the right tool for the right job.
Personally I use Python as much as I can: web development, machine learning, writing CLI, API integrations, web services.
I use Java when I have to, like making an integration with a SDK that only supports Java and it’s not possible to go with Python.
When I write system scripts in Linux, I use Bash/Shell scripting extensively.
The same reasoning goes for many other languages and their usage.
However, if your whole purpose is to learn, you’ll enjoy Python since it’s friendly for learners and you can pick it up in a couple of hours and be productive with it.
Alireza Savand • 2017 Nov 29