I use both and I use them for different purposes. I use org-mode to stay organized, track todo's, keep notes, etc. I use AsciiDoc to express myself to others, write documentation, and write blog posts. Certainly there is some degree of overlap between the two, but I, personally, don't find org-mode great for writing content to show to others, where-as AsciiDoc is designed for that. Also, there is an AsciiDoc exporter so you can turn org-mode content into AssciiDoc.