I would buy the PS3 if I had the money, but I'm waiting for the slim version to come out, so the prices drop
And yeah, Assassin's Creed is a must! I'm playing it on my Laptop...
a friend lend it to me
As for SO4... I don't know in which platform it will perform better. I never played the 360, but I have tried the Ps3... I think they're pretty much the same... depending on the game.. some better others not so..