Actually "kotlinish" is not allowed to be used as I read yesterday in the brand usage guidelines. 😄
Anyway, my recommendation, use TOML if you can, use DSL if you need. The TOML has some restrictions, like when you need to parse some other format, or when you need to do some calculations and so on, which you can solve using the DSL. But if you use the TOML, the build logics class path does not change if you change it, when using the DSL it does. So with the TOML chances are better to avoid unnecessary work.