Elixir/Erlang is the most underrated lang imo. Erlang was built for phone networks with fault tolerance and efficiency at it's core. Elixir makes it nice to use.

It was a bit tough to wrap my head from oop to functional programming and the syntax. That said I only played with it for a few weeks a couple of years ago with no real world project but I always wondered why it is not more popular in the bitcoin space compared to Go and Rust.

It seems to be a very good choice for relays imo.

The only drawback is that their package manager is called hex, but to their defense it existed before the shitcoin.