Finally, which one is the best : Gears of war 2, Killzone 2 or maybe Halo 3

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i dont want to say killzone 2 just because im a PS fan but i have to
i liked halo 3's MP but didnt like SP... i got bored of the MP after a week
i liked gears 1 but i didnt like gears 2 or should i say gears 1.5
i liked killzone 2's SP and i love MP
so for me killzone 2 wins