I've used both, Scala and Kotlin, and I like Kotlin very much.

A programming with more features is not necessarily better. The limited features of Kotlin (compared to Scala) are an advantage, if you change your point of view. Some advantages:

  * easier to learn (a Java dev will be more productive than in Java in a day or two)
  * easier to maintain since Kotlin doesn't allow so much hard to understand code constructs
  * fewer discussions about the one true style or way to do something
  * it's easier to build good tooling
  * much faster compilation
  * smoother Java interop
  * performance implications are more predictable