Elixir (or plain Erlang) by far. http://blog.plataformatec.com.br/2015/06/elixir-in-times-of-...
Edit
A few more reasons:
- Elixir/Phoenix outperforms quite everything for some usecases https://twitter.com/julianobs/status/614416512825323520
- Elixir Code is well suited for longer maintenance modes http://blog.plague-dev.de/posts/Maintainable-Code-in-Elixir
- Elixir unions the advantages of monolithic apps and microservices and is very easy to scale http://blog.erlware.org/monolith-vs-microservices-where-to-s...