Some markdowns have some nice features:
- Fenced code blocks, which I would prefer to prefixing with colons (update: oh I guess org-mode has an equivalent! good)
- Footnote support
- Definition list support (<dl><dt></dt><dd></dd></dl>)
Additionally, it should be noted that Markdown allows usage of any HTML you want and it will be passed through. In practice this is often sanitized or escaped, but not always. On GitHub, for example, you are perfectly free to use <sup>, <detail><summary>, and so on.
Update Nice, Org-Mode does all that? Then that is a strong advantage over Markdown, where you never know which parts of which flavor will work on what site. (Heck, we can’t even get GitHub and StackOverflow to treat code blocks similarly.)