Those one or two issue stories that you just really enjoy reading.

For me, I really like Robin #85, which is just the Joker explaining the history of Robin in his own twisted and demented way. I can't help laughing hysterically whenever I read it.

I also really like Superman/Batman #78, where all it is is 2 kids arguing who would win in a fight; Superman or Batman. It's such a simple story but I still love the fact that practically every comic book reader can and have put themselves into this exact same conversation.