It’s always interesting if we can find a discussion under a PubPeer article with more than 3 comments. Elisabeth Bik collected some of these interesting #PubPeer Pearls at Twitter while I am starting a new collection here.
The longest thread that I remember is this one with 290 comments around a retracted article while my most appreciated PubPeer authoris Guillaume Cabanac who seems to be a real person presenting there the most interesting findings like this one