This is the sort of thing for which the Internet was invented: cataloging all of the Yankees and Mets references in the history of “Seinfeld” and naming the top moments for each team within the show’s universe. Here’s the Mets. Here’s the Yankees.
For what it’s worth, I think that despite all of the great Yankees stuff due to George’s job as the assistant to the traveling secretary, the Mets got way better comedy moments in the series thanks to the magic loogie and the whole Keith Hernandez story arc.
But then again, I’ve always been a NL guy.