Who is the best female horse of all time? Ruffian or Zenyatta?

Why do you ask the same series of questions every day with a different name. Do you have some kind of weird horse racing fetish?

This is a tough question and as other contributors have replied, one can't really choose between the two horses as they competed in different eras and had to face different types of opponents in different conditions. Ruffian's career was cut short due to her tragic death while Zenyatta retired on her own terms. I have not watched a lot of Ruffian's performances as she raced before I was born, however I have watched most of Zenyatta's races which were excellent, for lack of a better word. Recently, I played this game called Horse Racing Fantasy where I pitted these two legends against each other along with other great horses such as Secretariat and Man o' War.