Introducing the Twelfth Doctor if he were ginger.
The nerds among you would know what the Gallifreyan at the bottom says.
I hope Peter Capaldi's Doctor has a beard; it makes him look saturnine like Three's Master. I imagine him to be colder, calmer, harder, more calculating. A combination of Two, Seven and Nine, with Three's penchant for delivering beautifully mistimed insults.
I imagine Twelve's reaction would be the above, after all the fuss of Ten and Eleven not being ginger, Twelve (the Doc does change his taste with each regeneration, after all) would consider being sort-of, kind-of ginger a humbug moment. I think he'd be more concerned with his attire.
If the others ever became ginger, however:
Two: Oh, dear. Oh, dear me..
Jamie: What's the matter?
Two: I'm ginger. Oh, dear...
Jamie :You look like a Highland beastie!
Two: I certainly do not!
Three: Good grief!
Brigadier: What's the matter?
Three: I'm the gingerbread man!
Brigadier: Good heavens, Doctor, people are dying and you want me to tell you how handsome you are?
Seven: Ginger hairrr. Hmm...
Seven: That depends.
Ace: On what?
Rose: What is?
Nine: I'm ginger with a northern accent!
Rose: You're so vain, you think the universe is about you.
Nine: Sort of, yeah.