For storage of structured data (and probably even for loosely coupled RPC) you want format that is efficient and schema-oblivious. The bad choice 15 years ago w

For storage of structured data (and probably even for loosely coupled RPC) you want format that is efficient and schema-oblivious. The bad choice 15 years ago was XML, bad choice today is JSON (the parsing overhead is not negligible) or ProtoBufs (not schema-oblivious). Various binary formats with JSON-like object model seems like the way to go (my choice is CBOR). And then there is the EU-wide absurdity of WhateverAdES, which invariably leads to onion-like layers of XML in ASN.1 encoded as base64 in XML wrapped in CMS DER encoded message...