A good system uses both but it's not trivial to blend them. My system is right now showing me maybe 30% of what it ingests, if I was seeing just 3% I'd have to cut back more harshly and a popularity score would help. Fundamentally a popularity score has a much larger dynamic range than a relevance score.
Google has both a document-query relevance score plus a document quality score.
I've heard from a lot of people who like reading HN from a comment-centric point of view and I tried feeding all the comments into my system and it was really too much. When I fed in high-scoring comments, however, I like the results. I had somebody suggest comments from Metafilter and I think that could be a winner but of course comments have a network structure of relatedness to other comments and the submission that a comment-oriented reader could take advantage of.
Google has both a document-query relevance score plus a document quality score.
I've heard from a lot of people who like reading HN from a comment-centric point of view and I tried feeding all the comments into my system and it was really too much. When I fed in high-scoring comments, however, I like the results. I had somebody suggest comments from Metafilter and I think that could be a winner but of course comments have a network structure of relatedness to other comments and the submission that a comment-oriented reader could take advantage of.