Personally I prefer story mode if there is a plot line. I'm always held in suspense that way. Free play is the only option once you beat story mode, so it should be held in second regard.
i like story mode most of the time cus some of the plotlines are just plain cool, but free play gives u variaty and u can do what u want vrs intelligent(more or less) people,
well mostly cuz of how many scenarios and diferent ways things can happen i say free play is better
Story mode tends to be the game's focal point. I especially like games with strong storylines and striking plots. I also like games that have multiple options to choose from and multiple endings. Makes story mode much better.
Free play, if good enough can be the sole reason why people replay games. Games with good sandbox/free play modes are very fun indeed.
For me, I am strongly torn apart by the two and unable to make a decision.