Also Clojure is a gaining a lot of mindshare these days, and for good reason. Great data structures, profoundly good concurrency support (puts Scheme and CL to shame in this regard), and a great community. It's also relatively simple, CL is as at least as complicated as C++.
This isn't to say I don't enjoy CL or Scheme. I learned Scheme with SICP. And CL brought me to Clojure. It all depends on your goals I suppose. If you want to learn a Lisp that is immensely practical go for Clojure. Otherwise CL or Scheme are both great.
