Well, .... pelvic or groin WOUND is good, especially if it hits the abdominal aorta or one of the femoral arteries and makes a big enough wound. A wound in the heart would almost certainly rob the brain of oxygen in mere seconds. A large enough wound to the main arteries or veins of the lungs will lower blood pressure quickly.
Notice that I said "wounds" and not "shots". Under the stress of a deadly attack, with an attacker who may be moving, while attempting to move oneself in order to minimize chances of being hit, the best strategy for making any of these wounds in an attacker is to aim for center-of-mass.
If one were to aim for the groin and the shot goes low, the attacker may actually escape being wounded at all if the round goes between his legs.
The thoracic cavity is rich in large arteries and veins. Most people don't realize that the abdominal aorta is a pipe which is about twice the diameter of a garden hose. Put some holes in it and the attacker will quickly lose the ability to continue the attack.
Movies and TV make it appear as if a gun is a magic wand. Shoot someone and they immediately fall over unconscious. Some people when wounded will immediately lose interest in attacking. Others who are more disciplined or who are under the influence of drugs, can continue the attack despite having taken several rounds, even if the wounds will eventually prove fatal.
I remember an old detective movie with Dan Blocker (Hoss from the Bonanza series) having somebody point a small caliber handgun at him. I think he laughed and said, "You've got to be kidding!".
The point was that a man built like Blocker might be killed by several rounds from a small handgun, but that it was very likely that Blocker would have been able to close on the shooter and break the shooter's neck with his bare hands before suffering much in the way of ill effects.
The infamous shoot-out of the FBI with two well-disciplined and well-armed bank robbers demonstrated that bad guys can suffer many wounds and still have the ability to kill the good guys.
If you are attacked and can run away, then run away. Otherwise, make use of cover or concealment and use whatever force you have available to stop the attack. Running away is always the preferred option because the outcome of a gun battle is always uncertain. It's poor consolation to stop the attacker if one ends up dead.
I offered that as an alternative to a head shot. Like in case you could’nt get a clear shot there. Besides you mentioned wearing a vest, and generally the groin area is unshielded, has arteries and might cause the perp not to be able to advance towards you if you hit certain internals.
Plus if you aim high, you have a better chance at hitting his torso. Aim high on a head shot and you hit nothing.