Empire Strikes Back
When I was younger I loved ANH the most, but when I got older, I started appreciating ESB a whole lot more, even though I always did love it.
It's the training scenes on Degobah that make it so. Yoda is written superbly. Everything he says applies to real life. Just Hammil's interaction, Oz's master puppetry, make you really believe in him.
I just love the screenplay. Period. It's just the best of everything. The ending is a cliffhanger but it doesn't feel that way, not like DMC.
I love the interaction between Han and Leia, my favorite on screen romance of all time. Gradually, in ANH, they can't stand eachother, but you wonder if thewy could be together, and in this film, they still can't stand eachother, on the outside, but really they love eachother. The dialogue, when they're on Hoth and in the Falcon is gold. Pure gold.
Vader is ****ing badass in this film. When I was young it always disturbed me how many people he killed with force grip. Plus, the back of his head is revealed.
Boba fett is introduced of course, (his original voice FTMFW) And Lando Calrissean!
And the carbon freezing scene is one of my favorite all times scenes in the saga. But the battle between Luke and Vader is still the best duel in the saga.