Which language should I choose?
All those are nice languages, but Rust is harder to learn properly and has a smaller ecosystem. If you want to work in system programming (like hardware drivers) Rust is probably your choice. Otherwise, Java/Kotlin ecosystem is much larger and gives much more possibilities (maybe excluding low-level system programming).
When talking about Kotlin and Java, both are good. But Kotlin, again, gives much more opportunities. Kotlin-JS gives you browser applications, Kotlin-Native allows to compile to native application (and interop with them). Kotlin-WASM will be available shortly. Rust is better than Kotlin-Native for native development tight now, but not by far and it makes sense only if you are focusing only on native development.
I will highly recommend Kotlin. I have worked with all three intensely and so far the development speed and simplicity is the best with Kotlin. Kotlin supports coroutines out of the box. Now, it isn't something that can't be implemented in other languages but Kotlin makes it super easy to work with them. Kotlin has a bit of learning curve, so, by the time you can actually use it idiomatically chances are that you will get proficient in Java too. But once you get it, you get it, then there is no other language ;) Kotlin is backed by Google and Jetbrains team so you can expect latest programming features and good community support.