Node.js or Erlang

Question

I really like these tools when it comes to the concurrency level it can handle.

Erlang/OTP looks like much more stable solution but requires much more learning and a lot

Answer 1

There is one more language on the same VM that erlang is -> Elixir

It's a very interesting alternative to Erlang, check this one out.

Also it has a fast-growing web framework based on it-> Phoenix Framework