I have an other entry for this duel, where I explain how the battle is not short:
http://blogs.starwars.com/saberb/1
but I come up with a second one (this one), where I explain why a fan should favorite this duel among others.
So, here we go:

Reasons we like the duel:

1. It's climax. Everything depends on that duel, the fate of the galaxy. It results the redemption of Anakin Skywalker, the death of Palpy and everything else.
Just think: If Vader won, the saga would have ended in a very different way.

2. The fact that it's the final one. It's the last G canonical confrontation between Jedi and Sith. It's the "final duel". It is exciting only to hear that.

3. It's music score. Dramatic, breathtaking, emotional and stunning, probably the best music in the Saga. Astonishing.

4.It's lightsaber action. Not the best duel in terms of action, but still, a very good one, Luke's kick, Vader's saber throw etc.

5. It's emotion. Father vs Son for the fate of the galaxy. None of them wanting to kill each other. Only turn each other. The best in terms of emotion, hands down.

6. It makes you nervous! Not only it is not short (for reasons explained in http://blogs.starwars.com/saberb/1), but it looks like it is the longest ever!
I wanted to skip it to see the winner! To die for! It takes 'em forever!

One of the greatest lightsaber duels, if not the best (the best to me).

Also see: http://blogs.starwars.com/saberb/1

PS: Is that Vader on the picture?