For human-readable document content, there's nothing wrong with plain old HTML, though formats like RST or markdown are somewhat easier to produce. (I save my b

For human-readable document content, there's nothing wrong with plain old HTML, though formats like RST or markdown are somewhat easier to produce. (I save my blog documents in markdown format - they're just easier to write and update, and I don't have to futz around with JS-heavy WYSIWYG editors.) However, these aren't adequate for structured data that falls outside the scope of a generic print document. For that, I would recommend YAML or JSON over XML, not only because they're human-readable but also because they're far less verbose.