Zaps are mostly an artifact of follower-count, like reactions and reposts. Quotes and replies are the only high-signal responses, as far as I can tell. And only if the responses carry information and aren't from real or artificial reply guys.

Well, and air-replies (probably the most high-signal, as it hints at some controversy or disagreement), but you'd need AI to find those, probably. 

 if quotes just count toward the ranking of the note that they are quoting, it won't draw any attention to the quote itself. it does seem like quotes can be a higher signal than other mentions (likes, replies). how would you suggest handling quotes in the nostr algorithm? 

 I'd focus on the note they were quoting.