Which of the Call Of Duty games...is the best in your opinion? (Ive been really wanting it...but not sure which one to get. Thanks!)

1-3 are good, COD 2 big red one is amazing (in both single and multiplayer, one of my favorites), Black ops 1 and 2 are good, and MW2 and 3 are pretty good, as far as MW1 I don't know because I've never played it, and ghost well the story is good but not the multiplayer.