If you are able to find hollow points that produce a muzzle velocity of at least 1,300 fps in your weapon that will help to ensure adequate soft tissue damage and more rapid incapacitation of your target. Heavier bullets are more adept at penetration of soft cover, clothing, and bone.
If your carry weapon is chambered in .45ACP, .40S&W, or .38+P then you should focus on the lower mass / higher velocity end of available defensive ammunition. With .40 and .45, you have adequate bore diameter to afford the lower density of solid copper, which typically outperforms jacketed lead. Magtech, Doubletap, and CorBon make loads of this type.
If your carry weapon is chambered in 9mm+P, then velocity is less of a problem and you should look at the heavier end of bonded jacketed lead hollow points. Polymer tips may prevent inadequate expansion. Hornady and Nosler both carry polymer tipped options.
If you carry .357mag, .357sig, or .44mag then shoot any quality hollow point you want.
Of course, ammo choice doesn't matter if you can't hit your target. In my opinion, all handguns (except .44mag) are underpowered and you must be prepared to fire the full magazine/cylinder capacity of your weapon and hit the target with every round, every time. It's easier to practice often if you enjoy shooting your carry weapon and it is cheap to feed.
For what it's worth, I am an engineer and I conduct research in armor protection systems. I live just outside a large city with frightening levels of violent crime. I carry Buffalo Bore 125gr Barnes expanders in my .40 shield. (product 23D/20)
Have fun shopping for ammo and try not to spend too much.
