It's time to rank these things. Note, this poll includes only the duels featured in the seven feature films to date. If I tried to include Clone Wars and the EU - ahem - and Legends, we'd have more options than the forum's polls will handle. I also include only saber-on-saber slashing (i.e. Mace Windu's decapitation of Jango Fett doesn't make the cut [pardon the pun], nor does Luke's fight with the Speeder Troops on Endor's Moon).
I include a spoiler in the thread title only because the poll inherently gives away who will be swinging lasers in the latest film. That's a minor spoiler (if spoilerish at all), but better safe than sorry, given that mobs have pummeled spoliers in the street.