I was going to be a smart ass and say a good 45acp, but in the hope of not starting to much of a flame war, all I will say is that I have not loaded any 9mm ammo for close on to 20 years. After I sold my last Hi Power I did not have the need. However if I was going to use (either with factory or handloads) a 9mm for home defense I would buy or load some with some good JHP bullets in the 115g range. Then take them to the rifle range and test them. Soak 20' or so of newspaper or phone books in all the water they can suck up over night. Take those to the range and shoot them with your intended load at 3, 6, 9, 12, and 15 yards. Or what ever range makes the most sense to you and your situation. You also might try and wrapping the paper in several layers of old jeans or something and see if that has any effect. Some, have in the past, reported that some HP bullets could sometimes plug with cloth and so not expand.
I would not place to much faith in the "Heavy" but slower bullets in the 9mm. Go for a light to medium weight HP moving fast. Then maybe, if your lucky you might get a permement wound cavity as deep and as wide as that of my 225g WFN out of my 45acp. (I tried, lord knows I tried)
YMMV and as always my advice is worth exactly what you paid for it.
Grendel
People who are willing to rely on the government to keep them safe are pretty much standing on Darwin's mat, pounding on the door, screaming, "Take me, take me!"
Carl Jacobs