I've used Java, Erlang, and Elixir professionally and I would never go back to Java. I like being able to write code without the crutch of an IDE. I like not having to deal with JVM deployments. I also like Erlang's functional paradigm and concurrency model a lot better. I'm at least twice as productive in Erlang and Elixir, so I view the two languages as having a competitive advantage over Java.