Don't learn a Lisp. For one, you'll end up in endless arguments whether your Lisp is a proper Lisp, and two, everything else will look ludicrously constraining for no good reason.
Main drawback of using a lisp for professional development is that it's really hard to go back to anything else afterwards. "Why use Assembly if you have C?" (unless you have a really good use case for it, of course), that's a bit the feeling you get.