What do you mean by "best"?
Basically what I mean is. Lets say a 190lb in shape man was going to be defending a 1,000 sqft house, at night time, and where only allowed 2 guns. You had unlimited money for this and in this made up scenario every gun is legal . Which 2 weapons would you purchase? Those 2 weapons would be the "best".
Now I am sure there is some sort of range where someone would say X is best, another would say Y is best, etc., but the "best range" has to be relatively small if we are to be completely honest and unbiased.