Which is the most useful programming language ?

Answer 1

It depends what you want to do. Python is popular because of the wide range if things you can do with and its convertability to C languages. Pretty much anaythig you can do with a different language you can also do with Python. You can use Spark with Python for text mining or Tensorflow or Theano for ConvNets. Guess its not for use interface sort of stuff but its good behind the scenes. Ruby is supposed to be good for app development and is a very in demand language.

Answer 2

java
JavaScript