AsciiDoc is pretty good because it's similar enough and standardized better. Also more extensible, yet a bit more complicated to get running.
One lesser known fact of AsciiDoc is that it's a markup syntax for DocBook, so it supports the full feature set of this book-creating toolchain. Markdown can only dream of having support for more than simple web pages and single-page documents.
The IntelliJ plugin is excellent.
And https://asciidoctor.org/docs/asciidoctor-diagram/ is amazing. I use PlantUML in it and love it.