Guns are pretty good for incapacitating someone, but notoriously unreliable for killing anyone, unless the gun happened to be fired by an expert marksman.
You'd have to be shot several times, and even then, you'd still be marginally conscious for a very long time before actually dying.
As for the whole taser thing, I think we should get rid of them. I prefer that cops carry guns. Yes, they are more lethal than tasers but that is precisely why I prefer it. The more lethal the weapon, the more hesitant the cop will likely be to use it to defuse a situation. Give them a taser and they think "Hey this isn't lethal, I can just bust it out whenever I want, problem solved!"