Language rarely matters, but Scala is were the action is today and probably in the future.

Both languages could be considered "add-ons" on top of their runtime, so you have to think about how likely it is that the "base" language gets good enough to slow down adoption significantly.

In Scala's case it's quite unlikely that Java will ever be able to even decrease the gap let alone closing it.

Elixir feels a lot like CoffeeScript in that regard.