My main languages are Ruby and Python (does SQL count?), but I dabble with Javascript when needed.
I have been liking Ruby more and more because of how easy it is to use and the community support it has. I have really appreciated RSpec, and that's the main reason I enjoy it over Python.
I really want to get into Rust because it is so different from Ruby. I am also a strong supporter of adopting a different language if you need to. I am not a fan of introducing types into Ruby or Python because there are other languages that have it built in and also the dynamic nature of those languages are their strengths.
I could see value in adding type checking to a codebase that is transitioning from exploratory to maturity without having to rewrite in another language.