I use Jackson. I am much more familiar with it and the Jackson Kotlin module works nicely out of the box (https://github.com/FasterXML/jackson-module-kotlin htt

I use Jackson. I am much more familiar with it and the Jackson Kotlin module works nicely out of the box (https://github.com/FasterXML/jackson-module-kotlin https://github.com/FasterXML/jackson-module-kotlin). Also Vert.x is using Jackson under the hood so one less critical dependency to think about. I think Gson is more common on the Android side of things where Kotlin has (I believe) a lot more popularity than on the backend.