This is a public Gist document on which you can comment if you have experience with both #CommonLisp and #Racket or #Scheme . The consensus is that the Common Lisp debugging and interactive "image based development" experience in a REPL (in particualr, using Emacs and SLIME) is by far the most reliable, robust, and user-friendly. Also, the fact that CLOS is standard, and there is no standard Meta-Object Protocol implementation for Scheme or Racket, really makes things so much easier.

I can't really disagree, but the reason I like Scheme is more for it's minimalism than it's developer experience. That said, if I were developing Lisp software professionally, I would probably prefer Common Lisp.