I would have to say Anakin's: "I HATE YOU" and the dialogue that followed were the most emotional. I really do like that part though. To me, it shows how noble Obi-Wan is, yet at the same time how evil Anakin has become.
Now... I'm gonna switch up the rules a little bit. Name the most emotional scene from the prequels, and then the most emotional from the original trilogy. Tell why as well.
Well, I agree. When Anakin said he hated Obi-wan it sent a chill down my spine. And Obi-Wan's breakdown was long deserved. He gets f-ed more than anyone else in the series really.
For the OT, I would have to say the final battle,of course. When Vader steps in to save his son it's just a splendid moment.