Kotlin, our company had recently turned into a java shop, and I was literally tempted to throw in the towel because I'm used to C# & python, so the boilerplate was really unpalatable.

Then one of our team wrote a service in kotlin, and we never looked back, I had my type inference, extension methods & null safety back, along with really strong immutability features, pure functions to boot.

It is such a pleasure to work with, it's in my opinion the pinnacle of traditional statically typed OO language (C#, java etc)

EDIT: now, all new services in our company are written in kotlin, it got grass roots adoption in every team (bar one which came from a much more old-school java background)