Madonna hasn't sold much more than Mariah or Celine - the amount sold between them is too close to call, that's how close the record sales are - and please don't quote Guiness World Records as a reliable source - they are paid to vindicate "records" by the people whom it suits.
Madonna certainly causes more of a storm than the other two, and has always been a big crowd pleaser, which is why I'd give her the Queen title, but for people interested more in substance over style, Mariah and Celine are the winners.