I think you would struggle (at least initially) to feel more productive in Scheme than Ruby / Python (although Racket seems like it would probably be equivalent to Ruby/Python in capability).

However, I'm concentrating on Common Lisp these days, and there are things about it (it's object system (CLOS) and probably macros) that feel much more flexible and productive than even Ruby or Python.

Here is the order of books I'd recommend if you want to explore Common Lisp:

  1. Land of Lisp by Conrad Barski
  2. Practical Common Lisp by Peter Seibel
  3. ANSI Common Lisp by Paul Graham
  4. On Lisp by Paul Graham (available online)
  5. Paradigms of Artificial Intelligence by Peter Norvig

  Then maybe:
  6. Art of the Metaobject Protocol