Killzone : Shadow Fall or Battlefield 4?

I will be pre-ordering PS4 but I am confused about the game I would buy bundled with it. I have zeroed down my choice to Killzone : Shadow Fall and Battlefield 4. I have never played any game of these series. I want a quality shooter game not the ones in which you just go on firing blindly over enemies. I saw the gameplay trailer of both KZSF and BF4 but what I saw was KZSF had great graphics but BF4 seemed kind of realistic to me. I want to know if any of these two games have stealth and is based on tactics that is, the player doesn't always have to take the lead position and role of the player is changed according to the situation.