I would go with Kotlin 90% of the time. It's faster, has better syntax, strong type checks, great ecosystem and community (Jetbrains, Spring, Google support it

I would go with Kotlin 90% of the time. It's faster, has better syntax, strong type checks, great ecosystem and community (Jetbrains, Spring, Google support it). It has some wicked cool Reactive support and scales pretty well. So I would go with Kotlin. Unless, you want to build a prototype and do not know the language. NodeJS may help you get started quickly.