I prefer the ESB duel all the way, both for choreography and story. I love the 3-act nature of it: (i) the initial meeting and ominous words from Vader; (ii) the oppressive atmosphere as Vader surprises Luke on the lower level, this time remaining silent while completely overpowering him with the Force - the music in that scene is intense; (iii) the final fight on the ledge and big reveal. The acting from Hamill when he learns the truth is incredible; his reaction still sends shivers down my spine.