(Assuming you're referring to config or related storage of data…)
Some people seem to prefer a particular ordering for certain items, and that can be enforced with schemas when using XML as a config language.
From a parsing perspective, however, JSON is one of the easiest, and it can be written compactly to save disk space or written with proper indentation and line breaks for human consumption. Tools and multiple draft specs for a JSON Schema format exist as well, though I'm honestly unaware of anybody using it. Of course,
JSON itself has its own troubles.
I say "No" to YAML whenever possible, and I have mixed feelings about TOML. Apparently
I'm not the only one with a distaste for TOML, and you can find plenty of hatred for YAML with little effort. The only advantage YAML seems to have is the fact that there's no need to match opening and closing delimiters as in JSON and XML, and it doesn't suffer from the DRY issues plaguing TOML.
I've seen some support for Dhall as a configuration language (and/or translator to JSON/YAML/Bash?), but I've not used it. It looks interesting/useful at least, though its feature-set make it much heavier than the other languages by comparison.
In my opinion, there is no single "universal" format that works for everybody, and that's fine as long as the format chosen works as intended. Projects may even change formats when one format becomes too cumbersome, and that's fine too, though ideally there'd be a tool to convert to the new format.