I don't know about the PSone or PS2, but I think the reason that best selling PS3 games don't do as well as the best selling Xbox 360 games, generaly speaking, is that a large portion of PS3 onwers bought the system as a Blu-ray player and they don't play games. Of the 37.3m PS3s in homes a lot of them aren't owned by gamers and as such no games are being bought for those machines. With Xbox 360 there are 42.7m in homes and all of them are owned by gamers becuase nobody would buy it just to watch DVDs or steam Netflix. So when a game comes out on Xbox 360 there are 42.7 potential buyers for it while of the 37.3m PS3 onwers it's hard to say how many of them will buy any games at all. In the console war a sale only matters if it's a gamer buying games. There are actualy less PS3s that matter in this console war than 37.3. I'm not going to venture a guess as to how many that is, but it does explain why the attachment rate is generaly mucyh lower on PS3 than Xbox 360 and why franchises, this generation, are strong on Xbox 360.
