I haven't used Erlang since 16 (maybe 17), but the two features that attracted me to Elixir were support for UTF-8 strings and macros. Erlang may have both now—I'm not sure—but doing localization in Elixir was a lot easier than it was in Erlang back in the day.

I would recommend learning both Erlang and Elixir. They're both amazing languages, I think, and your Erlang skills transfer nicely into Elixir, since you can call any Erlang function from within Elixir code.