Markup languages

So, /prog/. You are writing an application, and want to let users write in text with some basic formatting. Which markup language do you use?

I don't think the end-users are SATORI enough for teh S-exxxpressionz yet. So let's get down and serious;
There's BBCode, of course, but that smacks even more of web development than HTML does. A HTML subset might actually work okay, everybody knows some HTML, right?
There's also a gazillion different Wiki-markups, like Creole and WikiMedia markup.
reStructuredText looks nicer than the Wikis, but seems to be very FIOC-specific.
Or should I just let them attach a .docx document, or give them a WYSIWYG editor (faggot)? It's all your call.

HTML is the best.
Anything else is retarded.
With HTML, you provide your users with one of the two:
  * something useful to learn (unlike all the other solutions(
  * something that they are familiar with (because they already know HTML)

One thing HTML is not good at is that it does not provide sufficient layers of abstraction.
<br> is not as abstract as BBCode [#][br][\#], because the latter might translate (in phase 3) to whatever implementation dependant output.