This topic would be better if you could pick between two pianists who specialized in the same thing. Gould's strong point was obviously Bach, and not many of his other recordings are worth the time and expenses IMO. However, Horowitz specialized in Chopin, Liszt, and the Russian composers. They are very different because of the types of piano music they chose to pursue.
If you were to pick two pianists with the same strong points, this would be a more interesting topic. It would be less like Italy vs. France and more like: "Which part of Italy do you prefer, Sicily or Rome?"
Just a thought.
Phil