I don't know what the "best" defensive 9x19mm ammo is (if there is such a think), but I do know what my preference is: Speer Gold Dot 124gr (regular non +P). I like it because it's generally available in 50 rd boxes, is reasonably priced, and works very well in ever pistol I've tried it. I also like that POI shift is negligible versus the 115 grain and 124 grain cheap training ammo I tend to shoot.
It's not the sexiest, newest, or most powerful loading out there, but it has been around for years, it's proven, and it works as well as anything I've encountered.
It's not the sexiest, newest, or most powerful loading out there, but it has been around for years, it's proven, and it works as well as anything I've encountered.