I'm just going to write about seventh gen, if that's OK.
Microsoft: Made online gaming with friends easy, fun, and exciting. And supported the console with games that fit the model: Halo, Gears of War, Left 4 Dead, etc. Best controller on the planet.
Nintendo: Made a commitment to local multiplayer, created a revolutionary controller, and provided players with a huge assortment of classic games via Virtual Console.
Sony: Wisely invested in studios with tons of creative talent resulting in a handsome library of first-party titles. Made typically hard-to-find PS1 games like Klonoa, Final Fantasy Tactics, and Symphony of the Night available for a pittance at the Playstation Store.