They've had big games each gen dude. Plus they constantly innovate and come out with good hardware. Oh and they make new IP's each gen, where as Nintendo first party is still based around series' that started in the 80's.
PS1 it was Crash Bandicoot, Gran Turismo, Metal Gear, Final Fantasy, etc.
PS2 it was Gran Turismo, Grand Theft Auto, Metal Gear, God of War, Ratchet & Clank, etc.
Now with the PS3 its Uncharted, LittleBigPlanet, Resistance, Killzone, etc.
Not to mention great third party support.
I would argue Sony has the best first party games, in both quality and quanity.







