I don't think it's worth going from Java to Kotlin unless you have a real pressing reason. JVM languages have come and gone. None of them present enough of an improvement to leave the metric crapload of legacy Java code behind.
IMHO, for static typed lanaguages the most practical are Go or Typescript (if you wanna count that).
IMHO, for static typed lanaguages the most practical are Go or Typescript (if you wanna count that).