Interesting topic. Here are my choices (in no particular order of preference):
William, Duke of Cambridge - an intelligent, loyal and kind individual.
Queen Elizabeth II - a dedicated monarch, and I would love to hear some of her stories about her childhood and early life as a monarch.
Crown Princess Victoria of Sweden - appears to be a genuinely friendly individual, and does a great deal for her country.
Sophie, Countess of Wessex - I'd love to talk to her about the work she does with people who have special needs (especially children).
Duchess of Cornwall - she strikes me as someone who makes those around her feel at ease, and I'd love to know more about her charities.
Philip, Duke of Edinburgh - his sense of humor and opinions are rather entertaining to hear (and I'd love to hear his views on certain things, since he's not politically correct and would not be afraid to tell it like it is).