Here are some quick thoughts on why you might use each format.
An HTML sitemap was traditionally to help users find pages in your website, but they are also great for helping search engines find your pages organically. This is particularly true for websites with deep complex structures.
The HTML Sitemap can be linked relatively high up in your site structure and provide a direct route in to pages within your website no matter how deep they are in your website structure.
XML (Extensible Markup Language) Sitemaps are human and machine readable although they are generally more targeted to search engines. XML sitemaps are a great way to provide information beyond a list of links to the search engine, including details about when and how often pages are updated and how important pages are. They provide search engines more hints about the content of your website.
XML Sitemaps are supported by a number of the major search engines including :
RSS uses XML as well, but contains different content to an XML Sitemap. RSS sitemaps include more narrative about the content of the page including the Title, Description and when it was last updated.
Many search engines also support RSS sitemaps, but webmasters tend to favor XML sitemaps when working with search engines, however RSS sitemaps can prove a very useful tool in your SEO toolkit.
RSS sitemaps are generally more widely accepted for blog searches and directories because RSS is primarily used for content syndication. The result is ping tools such as our sitemap generator ping tool can automatically distribute them to more services.
This means you can potentially distribute your website updates more quickly and widely than with an XML sitemap. Due to the narrative nature RSS sitemaps can also help with external link building.