Ok, let's throw some hard facts in here:
Total sales figures:
NES: 61,780,000
Sega Master System: 13,000,000
Nintendo SNES: 49,020,000
Sega Mega Drive (Genesis): 30,750,000
Sony Playstation: 100,000,000
Nintendo 64: 32,930,000
Sega Saturn: 9,260,000
Sony Playstation 2: 81,390,000
Microsoft Xbox: 19,900,000
Nintendo Gamecube: 18,030,000
Sega Dreamcast: 10,600,000
Nintendo clearly dominated SEGA from the NES to the Gamecube. Sony outsold all of its generation's systems combined with the PSX and PS2.