What items should I get for a Yasuo top?
Solution 1:
Since your build is full damage and Yasuo's kit doesn't provide easy escapes (after burning flash), you need at least one item that favors survival.
I'll name the items that favors the most for Yasuo and explain why and when you must have them.
Guardian Angel : if you're carrying the game (meaning you're dealing most of the team's damage and perhaps being the only hope of the game), with proper positioning in teamfights you can either turn the fight in your favor or save yourself, which makes this item the best option.
Banshee's Veil : If you're getting focused hard either by cc or very high magic damage, this one is adequate. Shield denys one good large distance attempt of cc and/or damage and it's recovered after short cooldown.
Mercurial Scimitar (let me explain you with an example):
Say you have Orianna in your side, she ults the 5 of the enemies so you can ult them during airborne, but someone cc'd you to deny that possibility: Mercurial Scimitar's active removes all debuffs, so you can ult without a problem.
It could also work for when you're facing one or two important threats which has one but annoying cc (say Irelia's or Vayne's stun, fiddle's fear). However it's still very situational and it's active has a large cooldown, and thus I find myself secure with the ones above, since you need to react fast.
Solution 2:
Your question has a lot of possibilities to be honest. Most of the time you build full dmg as you have above. But it is very situational as well. If you are ahead and carrying build GA last or second to last. If you are loosing the game but you are playing will i would just build full dmg. If you are losing the game and you are doing poorly yourself you could build tankier early but you really wont be doing much of anything if the other team is way ahead.
My main recommendation would to just build full dmg with a tanky item second or last. Tanky item would be Guardian Angel #1, Banshee's if the other team has a lot of magic dmg, and mercurial scimitar if the other team has some deadly CC.