Functional languages

I want to learn functional programming. What language should I use?

Common Lisp
bigger community and usage, people like Alan Kay or Dijisktra said it opens your mind to higher levels, macros, Stallman recommends it

Haskell
Strong typing, pure functional, less weird syntax

Common Lisp isn't really that functional. If you don't want a purely functional language, you should at least go with Scheme.

If you just want to learn functional programming, I would suggest Haskell. Scheme and CL are great for other reasons.