Some great info here and some not so good. I'm not about to weed through 4pages to point it all out.
To answer the man's question: I need to ask a few questions 1st.
1.Do you have any formal trainging with firearms?
2. Are there children in the house?
3. Are you positive that if the time came to use the firearm, you will, with the full intent to eliminate the threat?
4. What is your budget?
Now, if you have no formal training stick with a revolver. If you do and can with out pause, clear a ftf, stovepipe, fte, then your options really come are endless.
If there are children in the house where will the firearm be stored?
If you can't fully comit to destroying the threat, do not introduce a firearm into the situation.
As far as budget goes, go onto www.gunbroker.com and type your price range and see some of your options. I'm not saying buy there, just see what guns are in the price range you have.
My opinion on a Great home, car defense gun is the Taurus Judge. 5 rounds of .410 or 45lc.
My opinion comes from 9yrs of military and 4 yrs leo. Check your local laws to see if you have any duty to retreat. In FL we have the King of the Castle doctrine and we have no duty to retreat.