Any 616 issue, it can encompass all of his titles (Web Of, Spectacular, Untold Tales, Sensational, etc.). I would have to say either Amazing #400 (The death of "Aunt May.".), or Amazing 121 or 122. They were probably the most powerful, on an emotional level. I didn't find Amazing #400 to be AS good or as emotional as it's acclaimed reputation, but it might have just been the most well-written single issue. As to the Ultimate question, I pretty much stopped reading the book after the third year or so, but I think that the most important one would have to have been the issue where Mary Jane learns Peter's identity (I forgot if he reveals it to her or not, I think that he did.), and the entire issue more-or-less revolves around them having a discussion about it. I'm pretty sure that it was issue #13. I really loved the first year or two of Ultimate. What do you guys think?