I've heard many different arguments for this. Some prefer the shocking level of detail and precision that a game reflects on real life (such as say, COD 4). Others might like the wanton chaos and absurd situations that a game provides, making the experience something much more unusual (i.e. GTA 4). I've seen whole reviews biased on one side or the other... and on rare occasions games can find a good balance between the two. But which game really provides the better entertainment value? (Not entirely sure if flexibility is the right word for the opposite of realism... didn't want to go with fantasy).