XML is still a huge mistake for most stuff. It's fine for _documents_ but not as a data storage solution. Bloat, ambiguities, virtually impossible to canonicalise.

XPath is cute, but if you don't mind bloat, text-only and lack of ergonomics, anyways then Conjunctive Regular Path Queries and RDF are miles ahead of XML as a data storage solution. (Not serialised as XML please xD)