Complete by-default null safety is a big point, extension functions are just nice, smart casts, proper data classes and operator overloading, and simple express

Complete by-default null safety is a big point, extension functions are just nice, smart casts, proper data classes and operator overloading, and simple expressive functional stuff like range syntax and reified generic types for inline functions. In general the Kotlin language feels more usable, yet less bloated (wrt the actual code, not the features ofc).