> I actually like XML. It isn't "cool" like YAML anymore, but it has better tooling support (e.g. schema checking) and doesn't try to be too clever. Just try to stay away from namespaces and don't be afraid of using attributes.

I agree with this (even though, In practice I usually just use JSON or YAML) - it avoids some of the pitfalls of both JSON and YAML - has comments, lacks ambiguity. The main annoyances are textContent (is whitespace important?), attributes vs children, verbosity of closing tags, etc.