Instead of equal, why can't we just say they're different?
They both have their purposes, their utility, and moments of opportunity. Yasuo's can be walked around, Braum will only block one projectile. Braum becomes tanky, Yasuo blocks every projectile that hits the wall.
Considering Braum can move around, it's fair the shield make him tankier but only completely blocks one blow. Yasuo's is stationary, so it gets complete defense if it blocks a projectile. Both have counterplay, both have weakness, both have strengths.
There's no point in arguing whose wall is stronger. Yes, Yasuo is an assassin. Yes, assassins are allowed to have a little utility. Yes, Braum is a tank. Yes, he has two tank abilities while Yasuo gets one wall.