PS3 may not have the bulkiest or most popular libary but I love the fact that it excels in quality in many genres.
Racing : GT5
3rd person action : Uncharted , MGS4
FPS :Resistance 2 soon Killzone 2
Platform : LBP
RPG's :WKC , Valkriya
I haven't got the chance to play Killzone 2 yet and probably won't unless some beta keys are given away next week.