As a long-time toe-dipper in functional programming waters, I am yet to appreciate the gestalt of any individual language. Going by Joey Hess of Debian and Git Annex fame, #Haskell is what is most bang for the buck.
I have found, though, that the most useful aspects, in isolation or in combination, are pure functions, immutable data and pattern matching syntax. Maybe you will find them in a language you like. Personally, I am enjoying foraying into #Prolog and #Erlang (or Elixir).
The first fully-developed prototype-based OO language was Self, original Javascript seems quite similar.