I think my motivators to do in Clojure were edn (dsl files are a key part of what I'm building), the concurrency story being strong, Java interop for libraries (Ruby wasn't necessarily missing anything but without the Java libs Clojure would not be an option), and a general belief that Clojure's overall approach (data oriented, LISP, functional) would prove generally more productive (I believe this is true but have no evidence since I never tried building it in another language). Spec has been an unexpected benefit as it saved me from writing a lot of validation code and because it can be used as a parser for the DSL (it does most of the heavy lifting).
How has your experience with CLJS? I have been using vanilla CLJ but curious to some day try CLJS.