lol, specifically I would pick WoW - You can play at least 27 times which each one will take at least two years to become MOSTLY complete 9 Classes 3 builds each, wait are there 9? Oh and the races, also engineering stats.... Seriously it's the best, but the fact you pay monthly is a huge rip-off, If it were between WoW of Fable 2 I would pick Fable 2, even though I never played it, you can play it becoming a Necromancer, Paladin, Wizard, Witch, Warrior, Pirate, even a civilian (Which I wouldn't prefer :P), priests, mages, all from one character - You choose if you be any, assassins or rogues, shamans and all sorts.... You can play the game MORE than 32 times and complete them all without being bored since it's such a great RPG, and how you play is so basic a 5 year old can play it easily, but it's still amazing, the storyline makes amazing sense (Although it is a Magic game too).... Best Single-Player game of all as far as I know.... And Call of Duty's are rubbish - They have way too many unrealistic flaws etc, if anything a Sniper is most accurate at hip fire in CoD4..... It sucks... And trust me it could be MUCH better
But out of them, if you didn't have to pay, WoW, anything else I wouldn't pick since I don't know them :P