After taking a gun safety class and studying police boo-boos (accidents discharging weapons) I have come to the following conclusion for home defense:
Shotgun (pump action). Most indoor engagements occur at about 14 feet distance and a shotgun produces a nice broad pattern at that range so it is hard to miss.
I have never shot at a person and hope never to but it I am told by the experts it is very difficult to do. Shooting a person with a handgun will at 14 feet will be extreemly difficult. Police, who have been trained find it very difficult to hit their target with a handgun - get a shotgun.
If you absolutely insist on a handgun get a revolver - not a semi-automatic pistol. To many things to remember to shoot a pistol (term I will use for semi-automatic). Pick up a revolver and shot - no thought process. Pick up a pistol - fee, is the safety off? Is there a round in the chanber? Is there a clip in the pistol. Again, pick up a revolver and shoot it. Last, for home defense with a handgun use Jacked Hollow Points (JHP). Less likely to have other issues like shooting the neighboor and the JHP has much better stopping power. Though Glaser bullets sound like the best home choice they just don't have the stopping power.
You want something that won't require a lot of thought on your part - again a shotgun. A bad guy entering your home will know what the pumping action of the shotgun means even if he hears it in another room - he will run. You are nurvous, shaking, you can still hit the man with the shotgun.
Actual, police shooting story: Two policemen, one bad guy in a shootout. Distance 15 feet. 32 total shoots fired from both sides - no one hit. Don't laugh - if you think shooting someone is easy go to one of those cardborad people shooting ranges and try it on cutouts figures of people and see out hard it is.
One last thought - ask our Marine friend in this thread but if he has been in combat I bet he find it harder to shoot accurately at close range than longer range - why? My thought it that it is less personal at long range. When we look a man in the eye the whole dynamic changes.