They are all fine languages. There is another (key) reason why Python is keeping its momentum: the availability of skilled, professional python developers with a lot commercial experience.
I've been called in a number of times to help out small businesses or teams that've started using Python because they were: researchers, scientists, or even just regular developers, and have found themselves with a growing business and customer requirements. Having a large, professional body of capable of (especially contract, here in London) developers makes a world of difference. You can find expert Julia, Haskell, Clojure, etc. developers -- but they are fewer and far between.
I've been called in a number of times to help out small businesses or teams that've started using Python because they were: researchers, scientists, or even just regular developers, and have found themselves with a growing business and customer requirements. Having a large, professional body of capable of (especially contract, here in London) developers makes a world of difference. You can find expert Julia, Haskell, Clojure, etc. developers -- but they are fewer and far between.