So, since you mentioned Java, Kotlin and Groovy are very pleasant to write and quite easy to learn, lots of syntactic sugar. I'd say Kotlin is a better language than Groovy. Scala is a very deep language to learn, lots of fascinating features, just reading Programming Scala is amazing and totally recommended. The learning curve is steeper to get to more advanced concepts but it is worth it. Rust is not as difficult to learn as Scala, not so many features and concepts but it's a bit difficult to wrap your head around borrowing and lifetimes mostly, and some of the smart pointer stuff. I wouldn't recommend lisp or derivatives like Closure etc mostly because of the parentheses. It is said the last 3 pages of the code that controlled the Soviet nuclear launch codes written in Lisp are just ending parentheses.

To scratch your itch of broadening your horizons and learn lots of amazing features that don't exist in the languages you know (Python, JavaScript, Typescript), I recommend Scala