Not sure how old the other posters are here, but I remember experts exchange being useful up to that point. Then stack overflow slowly replaced it in the search results.
I had no idea experts exchange existed before stack overflow.
For me, it started showing up in web search results years after stack overflow became popular. And I was confused and annoyed why a copycat with pay walled features (even the answers IIRC) was given priority by search engines.
There were several years when it would be the top result whenever you searched for a tech problem. Back then usenet was already largely dead, was more about mailing lists and IRC if you couldn't find a blog or forum post that covered the issue.
