Which language, Python, R, Java, C++, or Lisp, is best to learn artificial intelligence?

C/C++

Number 1 programming language in robotics! Many people agree that C and C++ are a good starting point for new roboticists. Why? Because a lot of hardware libraries use these languages. They allow interaction with low level hardware, allow for real time performance and are very mature programming languages.

Python

There has been a huge resurgence of Python in recent years especially in robotics. One of the reasons for this is probably that Python (and C++) are the two main programming languages found in ROS (Robot Operating System).There are many other languages like prolog and lisp which is used in AI choose according to your requirement.