Elixir was a gateway to Erlang for me. I hadn't heard of Erlang before I started writing in Elixir, but all the discussion of why Elixir was so great revolved around Erlang and the BEAM. This lead me to Joe's distributed systems thesis and really changed how I approach writing code.

The syntax takes a bit of getting used to, but I generally prefer the language. I haven't found anything that's a nice to work with for web app development in Erlang, though; I do think the tooling around Phoenix is nicely polished.