In the fifth generation, the PS1 dominated the N64 and the Saturn with 104 million sales. The N64 had 33 million and the Saturn had 9.
In the sixth generation, the PS2 dominated the GameCube and Xbox with 158 million sales. The GameCube had 22 million and the Xbox had 25 million.
In the seventh generation, the Wii dominated the Playstation 3 and the Xbox 360 with 101 million sales. The Xbox 360 had 81 million sales and the PS3 had 83 million sales, beating out the 360 despite the 360 launching 1 full year earlier.
In the current generation, The PS4 has already passed the Wii U after only being on the market for 4 months. The Wii U had a full year on the market, being available for 1 year and 4 months to date. The Xbox One is currently in third place.
If you just look at the history, PS3 was Sony's only blemish, their only disappointment. A Sony disappointment is considered a great success for the Xbox. Xbox simply has lower standards, they're happy with last place and consider it a "gain of marketshare", lol. Sony on the other hand is used to being number 1, 2nd place is considered a disaster and a disappointment. When you look at how much success PlayStation has had over the generations, it's not hard to see why they're number 1 again.