I think I prefer
Catherine, I don't know why, but
Katherine is nice also.
Kathryn is not very appealing to me, it loses it's classic feel.
Katie is my favourite nn. I've never been a fan of
Kate,
Kat or
Kitty. I know three
Katherine's (this spelling) and two go mostly by
Kat and one always goes by
Kate.
HTH. :)