In my corner of the tech world, Python is by far the most used by QA teams and by the industry for this kind of work. Java would be used second most. But Java is a lot harder and clunkier to use.
Python is straight-forward and easy to learn.
You could certainly go with any of the 3 and be good. But IMO, Python is your best bet for the first language. And learning Python will help you learn Java and JS.