Without counting things like PPV reviews or daily threads, which answer to a reader's question, to the best of your recollection, has generated the highest level of comment, debate and heat?
I can tell you that by far the biggest pageview count for a reader question ever is the one about Andre's genitals, which is currently sitting at 17,000 pageviews and counting and has been demonitized by Google multiple times for whatever reason. I have no idea who keeps viewing that page but it keeps going like clockwork. As for meaningful interaction, I don't have any specific examples of it, but basically any time someone sends in a question about whether Montreal was a work and their theory as to why it was or wasn't, the place goes CRAZY for days. There's a reason it's a meme on the blog.
Of course the all-timers are stuff like the guy threatening to sue me for banning him, although that wasn't really an actual “reader question”, and the usual barrage of Lex Luger questions and Invasion rebooking questions. Again, there's a reason all that stuff is a meme on the blog.