[cryptos]

The point to tooling was based on the original authors assessments. My own experiences are a bit dated, but I had problems with valid Scala code that wasn't understood by IntelliJ. The reason was probably that this IDE relies on its own analysis and not on the official compiler and nothing has changed in this regard. But I'm happy to hear that you are satisfied so far.

The problem with Java/Scala interop is that you can hardly use idiomatic Scala code from Java, while this no issue with Kotlin.

You're right about patter matching. It is sad that Kotlin doesn't have more to offer. But Kotlin has some nice things not present in Java like named parameters with default values, (limited) reified generics, proper covariance / contra variance, extension methods, first-class functions and what not.