…I really want to disagree with you… but all you’ve done is state an opinion with no evidence so there’s nothing to argue about.
I will say though that I don’t think you can say that any one girl is more fitting to represent Key, or any single character for that matter. Maybe when only Kanon and AIR existed you could say just Ayu or just Misuzu represents Key, but ever since CLANNAD I don’t think its possible anymore.
Not only has Key always focused on groups of people within VNs since then, but it also feels very wrong to choose one VN to represent all of Key. Think about it. If you see Ayu or Misuzu at all in marketing these days its almost always with the other and Nagisa. You probably won’t see Nagisa without Tomoya or the other main CLANNAD heroines. You never see the Little Busters separate, or Rin without Komari or Riki. Key no longer has, if it ever did have, just one emotion, personality, etc. associated with it.