Valt:
Lips. He likes how soft they are and feels that he can show affection for you that way.
Shu:
Cheek. He likes the soft and gentle gesture while also being gentlemanly and kind.
Free:
Neck. He likes the rough and affectionate passion of it. He also likes to give you hickeys.
Diago:
Forehead. It lets you know that he loves you, even if he is shy about it. It also makes him feel tall, which is nice.
Ukyo:
Hand. It lets him feel like he is treating you like a lady should be treated. Even if he is a dick.
Quon:
Lips. He likes the coarse passion and love he can show my kissing you in the lips.