First Learn Erlang because after learned that, you see a new world and really opened third eyes 
even you learn Elixir but need Erlang because Have Great Doc for learn
everything from basic to advance after Erlang you learn Elixir and Phoniex its Amazing
after learned thoose you can come to Rust+Tokio World.
that is God of Concurrency with Best of Concurrency Model and ZERO abstraction and give
you High level of coding and complete Safe.
in Erlang/Elixir World you learn how solve if a process CRASH with supervisor.
but in RUST+TOKIO you never crash because write complete safe All thing from scratch
Why Rust+Tokio is better than (Erlang, Elixir, Akka, Golang)
Elixir => Dont have standard struct , wait you have but with treaky and when you want use amazing feature of erlang make problem for you, for example Mnesia is best i had ever seen for in-memory distributed but with elixir you have not good feel when using it because have not a correct schema of tables,
Erlang => Erlang is amazing but is slow BECAUSE in background tried make a always available system and avoid crashing system and meny many other things, BUT in RUST solved All this problem by compile time and make complete safe system, with great error handling i ever seen.
Akka => is Great but use a GC for whole system not like erlang/elixir GC per process , even use ZGC maximum 10ms pause time, have to much impact on cpu usage. have you must learned to much things and after all you saw all of that solved a bad background JVM.
Golang => is Awesome but not support Generic by default and again use GC for whole system
Rust + Tokio => Not Have GC, Safe from Scratch, Blazing fast like C++, with complete Safe system and ZERO abstraction and give you High-level code. Solved all things.
