Lisp Vs. Python

I am looking to learn another programming language, I am a bit of a newbie but I know C, Java, and C++ rather well and am looking to expand.

I am interested in AI so I am considering Lisp.
But I also hear python is on the rise so I am considering that.

Which should I choose and why?

Really, this is too bad that we don't have post count, date of inscription and karma in our profiles.