But what you get in Eps 5 and 6 is a sense of story to the fight. In 5, when Luke fights Vader, he's clearly lost the fight before it even begins. He's distracted and off-balance. Vader's the older, smarter and more skilled fighter. Luke tries gamely enough to begin with, but every swing he takes is turned against him. Vader's not going all out; he doesn't want to kill, so he bides his time and breaks down his opponent before going for a disabling blow.
You need to watch the fight more closely. At the beginning of the fight, yes, Vader is toying with him. He holds his saber loosely with one hand. He simply sizes Luke up as being no threat at all. "All too easy. Perhaps you're not as strong as the Emperor thought." Shortly after this, however, Luke escapes the Carbonite chamber, gives Vader a face full of exhaust gas, and kicks him off the platform. By the time we reach the gantry, Vader is going 'balls out' in his fighting. Even then, Luke connects a swing with Vader's shoulder, which is only saved by his armor.
By contrast, the eps 1-3 fights have very little sense of story to them. They're more concerned with "wow factor" and, to put a cynical hat on for a moment, with making sure that everybody gets a chance to look cool to boost the toy sales. I never got a sense that a character's emotional state is being reflected in how they fight.
You had your "prequel blinders" on. :) Episode 1: Recall the scene where Obi wan, Qui gon, and Darth Maul were separated by the force fields. Obi wan stood pensively and anxiously. Separated from his master, he's unsure what to do next. Darth Maul paces in his chamber like rabid animal locked in a cage. Qui gon... sits down and _closes his eyes_ in meditation. Everything you need to know about what these three characters think of this fight is right _there_.
Episode 2: Obi-wan versus Dooku - Watch the look on Christopher Lee's face as he mocks and taunts Obi wan. He clearly has the upper hand, and isn't afraid to show it. Dooku vs. Anakin - I liked this fight because it spent more time focusing on lighting and shadow than it did on the swordplay. Very indicative of the blurry line that Anakin is walking between the light and dark sides. It's the outcome of this fight (Anakin's dismemberment) that feeds his growing desire for revenge that he'll unleash in the next film. Yoda vs. Dooku? Come on! What fanboy who saw ESB when he was 6 in 1980 _didn't_ feel it was worth the 22 year wait to see him kick some ass. Best of all, as soon as the fight was finished, he reached for his walking stick. This simple act shows the nature of how a "true" jedi uses the Force.
Episode 3: You get _five_ saber battles here. Pick your favorite. My favorites were Mace Windu vs. Sidious (Come on! The head of the Jedi Order vs. a Sith Master? How much more "story" do you need to fill in the blanks here? Plus, as the event that finally pushes Anakin "over the edge", it's importance to the narrative cannot be overstated) , and Obi wan vs. Anakin. What needs to be said about it? Obi wan busts Anakin joining Sideous, murdering hundreds of Jedi (including children), and nearly murdering his pregnant wife. How much more motivation does Obi wan need at this point to turn to fisticuffs? Plus, you have the entire mythological narrative involving the Descent to Hell, eternal damnation, and attempted redemption. This fight, more than any other, shows two combatants who are pretty much evenly matched throughout the whole fight.
