The point isn't the quality of every single game on the shelf, the point is that every game is bound to appeal to someone, and in this, the Playstation 2/3's game selection would appeal to a much wider audience. The Wii's PRICE appeals to a large audience, but it's games are very narrow and do not stray very far from the typical nintendo "round and shiny" style with the same characters, people like me, who do not enjoy things like Wii sports, mario, zelda, or metroid prime...won't find much in a Wii. The 360's mainly got action/shooter/fighting games. And all but the fighting games are for, and usually better on the PC. If not only for the content, for the PC/keyboard combo.
But the playstation game selection is so large, that there is bound to be something for everyone, or for people like me, who enjoy unique fighting, racing, platforming, RPG, adventuring, shooting, puzzle, party, even side scrolling games...playstation is where we'll find the most of them all. Spyro the Dragon, Crash Bandicoot, Soul Calibur, Prince of Persia, Final Fantasy (Including Dirge of the Cerberus, good game), Tomba, Ridge Racer, Metal Gear Solid, Jak and Daxter, Ratchet and Clank (these two series have also fighting/action/racing games in their series' as well), Tekken, Killzone, Wild 9, Blasto, Croc, Syphon Filter, etc. Several of the games I just listed off are series, with up to five or six games in them. Some of them are games created by the same company, where the company made a similar game with an entirely different storyline and set of characters (a whole new world) once they made three or four games for one set. Several of the people who made those games intend to make new games with entirely new characters and world for the PS3. I can't list off so many different series or sets of characters, so many different types and styles of games with Nintendo or the XBox. Yes, a *few* of those series are also partially for the XBox or Nintendo systems, but the majority of them are Playstation exclusive.
...compared to the XBox's "Halo" which I can get for the PC, and Nintendo's generations of the same handful of characters and styles, I really can't swing any other way for my system of preference. Once the Playstation 3 gets that kind of library (while still being able to play all the old ones I just mentioned), I don't think the other systems will compare to the gamer who enjoys all sorts of gaming.