Elixir has different goals than Erlang - it aims to be general purpose, while Erlang is clearly a DSL, though the D there is kind of huge. Erlang may be a better source of knowledge of OTP because it lacks distractions and doesn't hide as much as Elixir behind a convenience modules/macros/functions. As long as you don't want to run on the BEAM but learn something to apply in other environments. If you think you'll be using the platform, go for Elixir :)