2 systems get this distinction.
Nintendo 64, changed the game and made 3D gaming legitimate.
Super Mario 64, Ocarina of Time, Wrestling games, GoldenEye, Perfect Dark, Turok, Waverace, Tetrisphere, Mario Kart 64, Diddy Kong Racing, 1080 snowboarding
Xbox 360, revolutionized the gaming market. The XBLA marketplace was so great and just classic after classic on that system
Skyrim, Fallout 3 & NV, Gears of War 1&2, Shadow Complex, Fable 2, Dishonored,Super Meatboy, COD4, Bioshock Series, Mass Effect Series, Oblivion, Sf4, GTA5, Tomb Raider, Batman Arkham A&city, Portal 1 & 2, Orange Box, a few decent Maddens, Borderlands, Pac Man DX, Specops the Line
Runner up to SNES, lot of great games there.