Old (Straight Up with bangs)
New (Straight Down unkempt mess)
I like the new hair after Itachi's Death, and Sasuke descent into darkness, it makes him look more evil (and a bit more emo lol) and it just makes him look like "Oh look he's so evil now that he doesn't even give a shit about his hair anymore, what a mess"
But since after Kabuto's defeat, Sasuke looks like that he's changing, would you like if he went back to his old style?
Maybe after he meets with the one who knows everything he will start using his old hairstyle again, or when he will become a good guy again.