Who's the best 1 v 1 duelist?

There are so many variables here... Early game I'd say it's a tie between Darius (when against melee), Aatrox, and Fiora. At level 6 it's a tie between Irelia, Darius (again against melee) and Tryndamere. At level 18 it is between Tryndamere and Jax.

irelia, in most phases of the game. tryndamere at level 1-2 and 6

why is yasuo on this list

Aatrox actually (in my opinion) has a fairly weak early game. Unless he can zone out the enemy and build up his bloodwell early for the attack speed, then he's not going to do very well.

I can't pin it down to one person, but Darius, Xin Zhao and Fiora are extremely strong especially once they hit 6 (though Xin Zhao doesn't have a power spike like the rest.) Xin Zhao can duel almost anyone at level 3 due to his CC, damage, heal, and attack speed steroid.

Xin Zhao would have to be very high in my list. Darius is good against people who like to kite. Irelia is really strong, but she relies a lot on her heal.

kha'zix? he has great 1v1 and the q is on like a 5 sec cd