Sure we can still find FTP and NNTP servers around but let's face it, they aren't mainstreams anymore.
So my question is to find out if there are some internet protocols that you absolutely loved but you don't get to use much these days.
I also miss XPath (https://en.wikipedia.org/wiki/XPath). It's still around, but CSS selectors have taken over most everyday use cases. But for writing frontend tests or scrapers, XPath can still be very handy. I guess it's not really a "protocol", but IMO it was a good standard that saw too little real-world uptake.
I actually like that the other protocols are less favored as I can share something over one of them and know that my servers will not be overloaded. People today won't bother using less popular protocols unless they absolutely really want access. That weeds out bots and low effort clients. Sometimes I want a level of friction to be a great filter so to speak. Sometimes I will use FTPS or SFTP or native Rsync and someone has to be really interested to bother. This is especially useful if my target audience are highly technical people or non-cellphones. There are phone apps that speak all off the protocols but most people will not install and configure them on a whim. An example would be: I share a set of files on a chat server. The chat server has bots that can crawl HTTP(s) but they know not how to speak SFTP. Only the real human will bother.
That's probably a long winded way of indirectly answering your question. My favorite protocols are anything that raise the bar to access. In some regard it brings back the old internet for me and weeds out some of the riffraff. This probably sounds elitist but that is not my intention.