I don’t think a female Doctor will do. No offence, but he is married and that would have to be taken into account with the storyline. I think it should be someone not well known outside of G.B. . I personally liked David as the Doctor, for companions Rose for the simple fact that she and the Doctor were in love and they played it so well and it played a big part on the show. Now with Matt and Amy WOW, what a relationship, best friends, son in law, mother in law. Just wow, I cried in angels in Manhattan. The Doctor finally had a family with him and traveling.