^^^ meh, the delivery on that one was pretty shabby. Plus, the line just seemed so cliche for some reason. I do agree with "I am a Jedi, like my father before me," as being a very powerful one. It always gives me that...hmm...what's the right word.... patriotic(?) feeling rising up from deep within. Inspiring to do great things or something.

As for my personal pick, I'd go with "Don't make me destroy you!" the delivery is great & powerful. Plus, Vader just totally owned Luke through the whole fight, toying with him along the way (if you know much about real sword combat, you can see many instances when Vader has a perfect shot to slice Luke into pieces, but either hesitates or intentionally swings wide b/c his goal is not to kill Luke, but to dominate him & strike fear into him, in hopes of turning him to the darkside too.) He's just rubbing salt in the wound at this point, essentially saying, "dude! i just totally owned your butt! give up already!" in a much more powerful and frightening way.