JSON is naive, lacks almost everything. But is supereasy to parse and read.
As funny as it sounds, XML is overspecified. Parsing is possible and predictable but supporting the full standard (all of them) is so much work that nobody does it anyway.
So, given the choice above, i'd go for naive simplicity.
XML just looks nasty, but IMO not worse than JSON. JSON is not easy to read, because brackets suck for deep nesting. XML nesting is 100x easier to read, because the closing tags tell you exactly what is closing.
In xml's they clearly overdid it. all the formats/substandards you listed... there is just not a single library that supports all of the standard.
And because implementations are so different, most users just stick to a single C library. That library, btw, is also incomplete and undermaintained.
So that's the problem with complex standards: they are hard to implement and support. Nobody does this, unless it is a business-critical matter.
And then you have whatever the hell OpenAPI uses.