I have used Erlang when elixir still had to emerge. Today, I am using Elixir, with Phoenix LiveView and OTP Genserver, Supervisor and ETS.

I would start with Elixir, if only because of its newbie friendly community. The Erlang community is reflected in the 'erlang in anger' book.

But if you need to deploy on a small platform, say 32 bit 100MBytes, Erlang is the way to go.