There are a couple I have in mind. Like many techies, I am a huge fan of RSS for content distribution and XMPP for federated communication.
The really niche one I like is S-expressions as a data format and configuration in place of json, yaml, toml, etc.
I am a big fan of Plaintext formats, although I wish markdown had a few more features like tables.
TOML instead of YAML or JSON for configuration.
YAML is complex and has security concerns most people are not aware of.
JSON works, but the block quoting and indenting is a lot of noise for a simple category key value format.
YAML is racist to Norwegians.
If you have something like
country: NO
(NO = Norway), YAML will turn that intocountry: False
. Why? Implicit casting. There are a bunch of truthy strings that’ll be cast automagically.