Give Android Studio a shot. Makes laying out the UI in XML a breeze with its excellent intellisense.
I don't know anything about Kotlin on Android, though.
I was impressed with the tools you get out the box. I've paid hundred (close to thousands) for similar tools in .NET.
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.