[Terretta]

ISO 8601 is least ambiguous, as there's no question of "endian-ness".

https://en.wikipedia.org/wiki/ISO_8601

YYYY-MM-DD

Yes, with year last, most of the world does it one way, but most of the audience are often from a part of the world that (a) thinks it's most of the world, and (b) does it the wrong way by shuffling endian-ness.

[marginalia_nu]

The killer feature of ISO-8601 style dates is that you don't need to parse the dates to sort them. Lexicographical order is chronological order. That's a pretty huge deal.

[contingencies]

This. Two additional benefits of this approach are it sorts correctly and it's already standard in China, which is effectively a whole heap of the world's internet population.