Of the Wii's top ten games on Metacritic, nine are system exclusives. PS3's top ten is littered with (under par in some cases) 360 ports and cross system commodities. The same goes for the rest of the list. Yawn.
So basically if you want brand new experinces and the very highest rated games, stick with Wii. If you want loads of cross platform mid rated games the PS3 is for you.
Seriously though, the PS3 has no killer apps. Not one.