Id suggest you use nothing smaller than #2 goose shot, and preferably #4 buck shot,
for personal close range defensive work. (Generally under 20-25 ft, inside most homes)
simply because your life , and legal issues youll face if you survive,
might depend on the results.
remember, if your going too shoot anyone , you damn well MUST be justified and most likely under immediate, and Obviously a potentially lethal threat,
if you feel the , un-avoidable need too defend yourself, or family
and you may only get one chance at that brief opportunity for armed defense.
keep in mind the major issue with shot smaller than about #4 buck is that it loses adequate penetration,
very rapidly past about 25-30 yards on something as large as a deer/insane rapist etc/
I have always thought that a shotgun is a bad idea if you are chasing/looking for a bad guy for you don't know how many there are and another(2nd) one can grab the barrel and take it away. If you stay stationary such as behind your bed and facing the door, your chances are better. I'll keep the high ground with a pistol and 17 rounds.
a bit of proper training and a rather typical riot gun designed for home defensive use,
like with most tools training and skill,
goes a long way toward making a shotgun a viable & effective choice.
if concealed carry is not an issue