After experiencing Android development with Kotlin, I will choose Kotlin again by default. Admittedly, my experience with the most recent version of Java is not there, but Kotlin has some things I never found in Java. It statically checks for possible null pointer errors, and you can define free functions (without a class definition). Another nice thing is being able to declare constructor parameters as fields at once, and also automatic generation of getters / setters with data classes. This saves a ton of boilerplate. Maybe Java has some or all of these things now, but last time I used it, it didn't. I don't see it as a tower of Babel, but you have to keep on learning.