There are a few of them

• first class JSON support
• Regex build into the language (you need them sometimes)
• functions are value.

Lambda is nice, I really like destructuring.
It has simplified so much code for me the last few years. :)

I'm somewhat fond of how function definitions and function expressions look identical. You don't need to remember some different syntax just to insert a small function somewhere.

I also really like that the language doesn't treat double quoted and single quoted strings differently. A lot of languages don't care either way these days, but it's still nice to not need to constantly remember to use double quotes like in C or Elixir.

Destructuring and the spread operator!

• I really like functions as first-class citizens, nowadays I don't even consider languages without this feature.
• Destructuring is also a great addition.

Bonus track: stuff I'd like to see added to Javascript

• Automatic currying in function invocations built into the language.
• Pattern matching.
• A special character to ignore values, like underscore in Python.

Destructuring, Higher Order Functions, Spread Operator, Arrow Functions, async-await for asynchronous programming.