[brudgers]

Common Lisp is better than Scheme or Racket in the same sorts of ways that Clojure is better. It's a full on professional tool. But it doesn't have Felleisen's Student Languages or Htdp/universe out of the box to facilitate teaching like Racket.

I've never explored Franz/Allegro because CCL and SBCL etc. carry less baggage because of their FOSS pedigree...it's a bias more against demo/evaluation versions than closed source.

[lispm]

I doubt that either Racket or Clojure are comparable. Racket is not professional tool - it's an educational tool. Clojure is a more or less thin layer over Java.