Sorry to be the idiot, but I actually like resolution in a film and in a series. I voted "Return of the Jedi" as my favorite of the movies, although "The Empire Strikes Back" is a very close second.

My favorite character is Luke Skywalker, for much the same reason that I voted "Jedi" as my favorite of the movies. Of course, Yoda is great, and I actually like the emperor in "Jedi" -- he has some classic lines, and I like the delivery: "Good. I can feel your anger. I am defenseless. Take you weapon. Strike me down with all of your hatred, and your journey towards the dark side will be complete."
"Oh, I'm afraid the deflector shield will be quite operational when your friends arrive."
"From here you will witness the final destruction of the Alliance, and the end of your insignificant rebellion."
"Now witness the firepower of this fully armed and operational battle station!" I could go on and on with this one.

Also, one of my favorite lines in the movie was at the beginning when Vadar arrives at the new Death Star and warns the Commander about the progress:

Commander: Lord Vadar, this is an unexpected pleasure. We are honored by your presence.

Vadar: You may dispense with the pleasantries, Commander. I am here to put you back on schedule.

Commander: I assure you, Lord Vadar, my men are working as fast as they can.

Vadar: Perhaps I can find new ways to motivate them.

Commander: I tell you, this station will be operational as planned.

Vadar: The emperor does not share your optimistic appraisal of the situation.

Commander: But he asks the impossible. I need more men.

Vadar: Then perhaps you can tell him when he arrives.

Commander: The emperor's coming here?

Vadar: That is correct, Commander, and he is most displeased with your apparent lack of progress.

Commander: We shall double our efforts.

(one of my favorite lines)Vadar: I hope so, Commander, for your sake. The emperor is not as forgiving as I am.

That's good stuff.

As far as favorite themes from Episode III, I cheated. The classics have a special place in my heart, and Darth Vadar's theme ("The Imperial March") and Obi-wan Kenobi's theme ("The Jedi Theme/Luke's Theme") are two of my favorites from the original series. However, I love the dissonance of Mace Windu's theme (reminds me of Prokofiev), so I voted for all three of those. Sorry.

You really opened up a can of worms with this one, Maciamo. Sorry if I got carried away, but I just love "Star Wars."