I'm enjoying the game on the 360 but I wouldn't choose a console just for one game. Try looking at the catalouge of games for the 360 and PS3 and see what appeals to you
Exactly what I was going to say.
PS3 you have got Warhawk and Heavenly Sword that are 2 good recently released games.
Up and coming are Ratchet and Clank, GT5, MGS4, Unchartered, Haze, Final Fantasy XIII, White Knight Story
Xbox you have got obviously Halo 3 and BioShock, the 2 big games recently released. And up and coming Ninja Gaiden 2, Fable 2, Splinter Cell Conviction (im pretty sure thats an Xbox360 exclusive?).
I cant think of any more must-buy titles off the top of my head at the minute for the 360.
But anyway it depends which games you prefer playing etc...