I disagree that a pistol is the best defense. There is no such thing as the best defense. Not for every scenario, and there never will be.
Also, relying on something other than basic technology is foolish. I would not rely on a laser in self defense situation. Will you remember to turn it on? Will it actually work in the one instant you need it? Fumbling around with something that is good in theory could cost you precious time and get you killed.
I deal with technology failing, and I hate relying on it at times. That's why I carry a compass into the woods with me even though I have a GPS unit. I don't really need either most of the time, but if worse comes to worse the compass has never let me down while my GPS has run out of juice. The GPS is great for certain things, but I will never entrust my life completely to something that needs electricity to work.
A gun is a rather simple tool assuming you follow a few simple rules for self defense. Most self-defense pistols are safety-less now. That means you are the safety. You don't pull the trigger unless you have the weapon trained on someone you intend to shoot. Keep the gun well maintained, and practice with it. Get the use of it down pat so you can shoot without thinking. Thinking too much will get you killed, or get you into trouble with the law. If you have to think about whether or not you should pull out your weapon, then don't do it.
The best defense is the option that let's you live. Whether that be something that allows you to subdue/kill/frighten the criminal, or a safe room that keeps you alive. Living is the ultimate goal with self defense in mind. You are not a cop, you are not a hero, but you do have family and/or friends that don't want to see you dead. Never forget that simple fact.