Return of the Jedi, the '83 theatrical version is my all time favorite, bar none.
For the most part the SE changes to it were negative or added nothing. About the only change I thought was an improvement was the cleaned up Rancor fx in the '04 edition and the one shot of the cliffs flying towards the Dune Sea (who cares about the herd of Banthas, but the skiffs look much better, with them seeming to hover more and the guy on the deck not looking so stop-motiony).
The "new ending" of the 2004 Edition works as an ending to the entire saga (though I could have lived without "Wesa free!!!"), but it is distracting because it smacks me in the face with some of the lowpoints in the prequels.