Federal HST 147 grain 9mm
I am more impressed by penetration and expansion in gel tests than in muzzle energy or velocity numbers. After looking at all the gel test data I could find, I decided to go with Federal HST in the 147 grain size for 9mm defensive use. This is not a +P load, but seemed to make a deeper, wider hole in the gel than most other 9mm ammo tested. In the test linked below, this ammo penetrated 13.5 inches and expanded to 0.771 inches diameter.
Federal HST gel test data