Elizabeth I. As a child, endured almost unimaginable psychological pressure (horrific loss of her mother, religious turmoil, exile, constantly in fear of being used as a religious pawn and ending up like said mother).
As queen, dealt with more intrigue, back-stabbing, plotting etc. Understood image/make-up/clothes/jewellery like a pro. Ingeniously spun her 'virginity' as a positive.
Of the current lot, I agree with icefishing about Anne. Straight talking, and you always hear that she works harder than any of the others.