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.
I’d think they’d get it back by not having to share their ad rev with Google. There’s something to be said for the economies of scale Google benefits from but with cloud services that’s not as relevant as it was.