I'd say the Warchest although no call of duty has a set story Except for Modern Warfare 1 and 2. I would like to get Bf2 though.
Bitch Fortress 2? What?BF2...?
CoD 1 had a story, what the hell are you talking about?Anyway, BF2 isn't that good. Go for the Warchest.
Set Story as in none of the games connected to each other. Except for MW1 and MW2.
BFBC2 or BF2, go for it.
"set story" isn't an actual term.