Xin>Lee
Lee is flashier, but Xin seems to be more playable. They bring similar utlility...dive in either kill a squishy or insec a primary target, and do you best to get out. But, after level 3 I've never lost a 1v1 as Xin vs Lee. After you get red smite, its not even close.
The extra early damage Xin seems to have helps with early ganks, and he seems to not fall off as much late game.
Yes, at the highest of skill levels, a Lee Sin main should be able to out play a Xin Zhao. But, only like 10% of the player base could be considered that skill level.
So, wouldn't that mean Xin>Lee?