It pains me greatly to put such an iconic scene and revolutionary fight so low on this list, but at some point I'm forced to take the nostalgia-goggles off and face facts: this duel is small potatoes in the grander scheme of things.
It's wonderful in the context of Episode IV itself, but when stacked against the competition, its age shows. Amounting to basically two elderly gentlemen clanking some sticks together, the duel never comes close to expressing the true emotion lying beneath the surface of the former master/pupil dynamic duo.
Having said all of that, there are certainly hints and seeds of what was to come.
Visually, it is captured in glorious wide shots, that accent the full-body action in true Kurosawa fashion. Lucas also makes the most of the ever-compelling visual of the contrasting colors of 'laser swords' clashing together, and the innovative sound design for this showdown in-particular would go on to set the precedent not only for the franchise, but for cinema as a whole.