A lot of marketing and content-heavy sites showcase the page's primary content using large text and/or images, sometimes with a slider, containing a call to action for signing up for a service, or downloading an app, etc.. I'm not sure what this design element is called, I got the term hero unit from twitter bootstrap:

http://twitter.github.com/bootstrap/components.html#typography

I think most of you know what I'm trying to describe... If it's not clear I can add screenshots or links to this question.

I looked at a few different sites, and some put this hero unit inside a ASIDE element, others use SECTION, ARTICLE and even HEADER. Using twitter bootstrap as an example again:

<header class="jumbotron masthead">
  <div class="inner">
    <h1>Bootstrap, from Twitter</h1>
    <p>Simple and flexible HTML, CSS, and Javascript for popular user interface components and interactions.</p>
    <p class="download-info">

Is HEADER the most appropriate tag for this type of content? Or should I use ASIDE, ARTICLE or SECTION?