Ask HN: Favorite language features?

Hi everyone. This is my first post, so I apologize if I am off-topic or my submission is not within guidelines. My question is, what are your favorite features of any given programming language? And to contextualize, what do you do with said language?

Rust's borrow checker? Lisp's macros? Erlang's BEAM?

I'm new to programming in general and I realize many programming features are the results of tradeoffs but I still want to get a sense of what tradeoffs were most effective for what you want to do. I get that it is somewhat a matter of opinion and varies based on task.