Atari 2600 first real console magnavox oddysey was nice for its time but even though it was the first console it doesnt matter that much it didnt helped gaming. Atari 2600 createt the market.
NES saved the market after the big crash and changed gaming with Mario Bros and Zelda.
PS1 was the beginnig of 3d they showed how modern games will be N64 was aso remarkable but it gave birth to Nintendos 3d while PS1 was the platform for all developer. Also it made adults play and changed the kiddy image of consoles.
PS2 it has done everything what PS1 has done just better but is that all ? No PS2 changed the market PS1 brought the adults in and PS2 brought them all in. With singstar eyetoy Buzz guitar hero they also begun to bring in non player and unified all aspects of the market on one console.
Wii made the same thing as PS2 just in a larger scale. They brought in more non players and sold another console image to the market. And it was the first console which was remarkably weaker then the competitors.
That doesnt meant they are the best I prefer SNES over NES anytime. But those consoles actually moved the market and changed the way we look at consoles.
Sega was Nintendo (and later Sony) in another flavour even though I loved the DC they shouldnt be in that list. Also the N64 was really important but not as important as PS1. It was important for the Nintendo3dstyle. Xbox has life. true online gaming is big. But the havent changed the market in a similar way as the consoles mentioned above. Well the PS3 is imo the best console this gen but its actually a PS2 with more Horsepower and Online gaming. All the innovations in the PS3 didnt influenced the market in a way the Wii did.
Why PS2 ? Because the PS2 is still the best selling console and it actually begun to aim at non players. Which was later done by Nintendo even better. The PS2 created the market as seen today. Casuals Hardcore Nongamer those types were seen first time with the PS2 and not before. Again it just begun with it while this gen the whole thing expanded a lot.
