This is not quite a perfect "best of", it's extremely biased toward a few authors. But those authors (Henry Spencer, George Herbert, Paul F. Dietz, a few others) have an exceptional track record so the result is still an amazingly high quality collection of posts.
I really miss usenet, there was a time when it existed in a sweet-spot that fostered some quite excellent discussion. I believe HN is the closest analogue in the modern day but it's a pale shadow of usenet at its best, in my opinion.
I have very vivid memories of two particular usenet posts:
- Reading about a thing called "Mosaic" on alt.hypertext in early '93 when I was actually tasked with finding a hypertext browser for the project I was on. I remember thinking "Sounds cool, but why would I want to load documents over a network?"
- In '95 reading a post about a project called "Oak" at Sun that involved a guy that I vaguely knew, sending a begging email to Sun got me a very early copy of Java
