With the exception of the vaporware Gran Turismo 5, there isn't a PS3 exclusive I'd call better quality than a 360 exclusive.

Resistance: Fall of Man 1 & 2 = excellent
Gears of War 1 & 2 = excellent

Kill Zone 2 = excellent
Halo 3 = excellent

360 has nothing like Little Big Planet. PS3 has nothing like Viva Pinata.