Give Android Studio a shot. Makes laying out the UI in XML a breeze with its excellent intellisense.
I was impressed with the tools you get out the box. I've paid hundred (close to thousands) for similar tools in .NET.
I don't know anything about Kotlin on Android, though.
Android Studio only added Gradle, which provides Groovy for its scripting, recently. Groovy has a history of shipping standalone versions as soon as possible and letting users find the bugs, and only afterwards does Grails bundle the version. I'd say Gradle-bundled sits somewhere between standalone and Grails-bundled on the testing scale for Groovy versions.