Across 1,886 ranked games on patch 16.21 in Master and above, Yasuo mains win 55.0% of their games in the mid lane.
Their most common build appears in 65.6% of those games and wins 56.8% of its 1,237 games.
It starts 
two Health Potions and 
Doran's Bow, completes 
Immortal Shieldbow, 
Infinity Edge and 
Death's Dance in that order, and takes 
Berserker's Greaves.
Two other builds are played often enough in the mid lane to be measured on their own.
In the mid lane, Yasuo mains fare best against 
Sylas (won 66.7% of 33 games), 
Zed (won 63.3% of 49 games) and 
Aurora (won 66.7% of 24 games).
Their hardest matchups, the champions that counter Yasuo, are 
Yone (won 44.1% of 93 games), 
Orianna (won 40.4% of 47 games) and 
Akali (won 47.9% of 71 games).