That! Clojure is an elegant experiment with immutability. The implementation details of Clojure's datastructures are a pure joy to look at. JVM is an unfortunate choice as I see it, but it's a pretty solid system which is benefiting from decades of research on JIT, GC, etc, so not entirely unreasonable as a back-end.

I have few good things to say about Python, other than it sort of works. I classify it in the big-sack-of-stuff languages, along with Perl and shells. Not much elegance or style.