Eh, whatever console is in the lead, tends to have a ton of crap games. Back during the PS2/Xbox/GCN generation, due to budgetary constraints, I was Nintendo only, and frequently made fun of the PS2's shovelware (Ninjabread man came out on PS2 first, heh), same thing happened to the PS1, NES, and 2600. I also remember quite a few crap Genesis games.
As for which will have the better library, that's very hard to say, because it's subjective, speculative, and ill-defined (do you include PS1/GCN, Virtual Console, New Play Control, etc?). Lets just say both have their gems (God of War, Mario Galaxy) and both have their crap (Ninjabreadman).
Personally, I prefer the Wii/GCN's library, but that's mostly because I'm a big Nintendo fan. Someone who prefers other games could easily prefer the PS2's library. Such is taste and subjectivity.
