I loved the three-way lightsaber battle at the end of Episode I. It was the little things that made that battle. From the moment Maul appears in the doorway you know you're in for something special. Then when he draws back the hood of his cloak and you see all his horns for the first time...each time I saw it in the theatre, the crowd audibly gasped. Using the droid head to open the hanger complex door...good stuff. The little cocky stance after his quick exchange with Obi-Wan, shortly before Obi-Wan cuts his saber in two...magic.
The other moment no one seems to mention...the juxtaposition between Qui-Gon and Maul when the ray shield interrupts their battle. Qui-Gon meditates and calms himself in the force, while Maul prowls back and forth like a caged predator.
Another little moment...when Qui-Gon and Obi-Wan leap down from the castle overhang and easily dispatch the droids, the way Qui-Gon deftly hangs his saber back on his belt almost faster than the eye can follow. Oh, and where Palpatine says he will follow young Skywalker's career "with great interest."
Episode II: The entire battle between Jango and Obi-Wan on Kamino, including their war of terse words beforehand. Palpatine announcing "I will create a Grand Army...of the Republic..."
Mace falling from Dooku's box in the arena, on fire yet still deflecting blaster bolts all the way down. Jango's gun twirl after dropping Coleman Trebor. The evil grin on Dooku's face as he twists his blade around shortly before disabling Obi-Wan.
And finally, Yoda showing us all why he had the reputation of a "great warrior" in ESB.