The age-old debate. Branching off from the RotS thread so it doesn't go off-topic.

The way I see it, what really pushes these movies, above all else, are their dramatic elements and the execution thereof, which is why Empire is the best out of all of them. Here you have<ul type="square"><li>Luke almost freezing to death on Hoth, and Han risking his life to rescue him.
<li>Luke crashing on Dagobah, searching for Yoda, finding him, and learning the true nature of the Light Side--letting go of fear and aggression. And learning that even a tiny old elf muppet can lift an X-Wing out of a bog.
<li>The introduction of Lando Calrissian, one of the most awesome characters in the series, and the prompt souring of his friendship with Han when his dealings with the Empire are revealed.
<li>Han and Leia developing serious affection for one another over the course of the movie, only to have it end in a serious tragic climax. Carbonite, man. "I know." FOOM. This one is probably what seals it for me.
<li>Luke taking on Vader and getting seriously maimed--hand sliced off and all--and then on top of it, he finds out that the second-biggest jerk in the galaxy, the guy that <i>killed his father</i>, is, well, his father. This is the other big one, along with Han getting frozen.
<li>The bleak ending. Nothing special, but it counts.</ul>Compare this to Jedi.<ul type="square"><li>Luke's anxiety about causing hardship for his friends throughout the film. "I'm endangering the mission. I shouldn't have come."
<li>The death of Yoda and the sibling revelation. "There is another Skywalker." Leia's reaction.
<li>Luke's conversation with ghost-Ben about how he had lied to him about Vader.
<li>The razing of the Rebel fighters. The return of the Death Star. "It's a trap!"
<li>Palpatine and Vader's temptation of Luke, and all the violence that goes with it. Toying with his emotions and all. "If you will not turn to the Dark Side...then perhaps she will."
<li>Vader's redemption. Guy finally set things right.</ul>Seems about even, right? And it is. It really is. In fact, there's only one real element that drags down the quality of Jedi, but it certainly does a job of it. I speak, of course, of Ewoks.

If you look at the Star Wars movies in the sequence in which they were made, it should be obvious that there was a distinct movement on Lucas's part into what I call "cutesy mode." I'm talking about the kiddy-pandering, the goofy droids, the aspects put in the movies specifically with merchandising in mind. The Gungans, the pod racing, the conveyor belt scene in AotC. It was seen in full effect in Episode I, and is largely to blame for why the movie was so terrible. It was wearing off in Episode II, and by Episode III, it was, barring some wacky droid antics, finally, thankfully dead. But it all started in Episode VI--in Jedi--with the Ewoks.

Depending on how much a loser nerd you are, you may know that the whole Endor scenario in Jedi was originally the scene of a Wookiee slave uprising, but, as fuzzy as Wookiees are, they weren't considered marketable enough, so the slaves were replaced with a tribe of cute chirping little teddy bear creatures who demolish the best of the Galactic Empire's engines of destruction with Home Alone-ish traps made of sticks, stones, vines, berries, and love. Ewoks. This is why Empire is better.