Top Denny O'Neil Batman stories

Denny is one of the most celebrated Batman writers ever, and he had a very long run on the character. I've been trying to hunt down some of his strongest stories. So what are the top or what some think as "must read" Denny O'Neil Batman stories? The Joker's Five-Way Revenge (Batman #251) is the first that comes to mind, what else?

There are plenty of very good Batman stories by O'Neil

The one that come to my mind for now is "The strange deaths of Batman" because I read it recently

There are also the 3-issue story where KGBeast appear

His Ra's al Ghul stories specially Birth of the Demon, there is no hope in crime alley is also very good.