From worst to best.
Hayden
Greedo shoots first (and, apparantly, is a worse shot than the stormtroopers! How'd he survive as a bounty hunter anyway?)
Fett's voice
Jabba
Naboo at the end
Really, anything that changed the timing of the films. The films were brilliantly edited and never slowed down (well, Jabba's palace excluded). IF the changes had merely been cosmetic, I could have dealt with that.