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 agree Bluetooth (at least Bluetooth Classic) is not very well designed, but not because of frequency hopping. That improves robustness and I don’t see why it would cost any more power. The hopping pattern is deterministic. Receivers know in advance which frequency to hop to.