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.
To be honest, no. I mainly know about JPEG XL only because I’m acutely aware of the limitations of standard JPEG for both photography and high resolution scanned documents, where noise and real world messiness cause all sorts of problems. Something like QOI seems ideal for synthetic images, which I don’t work with a lot, and wouldn’t know the limitations of PNG as well.