I personally use 3" steel BB. I feel it's a good middle ground between buckshot and your lighter birdshot. (I live in an apartment complex so buck is not a good option for me). If you pattern steel, you'll find it spreads quicker than lead. The shot doesn't deform. The pellets actually bounce off each other. That's just what I want for my personal defense shotty. I've seen it used on meat targets and it performs outstanding, very good penetration and destruction. Steel is also lighter than lead so you'll find the manufacturers usually increase the velocity of the overall payload to achieve equal energy. One thing to consider, and it might not be an issue for home defense but don't shoot steel through any choke tighter than mod. That is unless you want to turn your shotty into a lamp stand. All this being said I don't think you can go wrong with just about any shotgun ammo.