For home defense I'd suggest buckshot and Imp. Cyl.. Most shotguns I've encountered always shoot a more uniform pattern with some choke. Cyl. Bore means no choke at all. Imp. Cyl. has a small amount of choke. I wouldn't go with anything more than Imp. Cyl. though, since you're not likely to shoot at anything more than 10-15 yards away in a home defense application.

For "rifled" (foster style) slugs I'd say Cyl. Bore or Imp. Cyl.

For steel shot I'd pattern a number of loads starting with Modified (mod.) choke. Generally, a given choke tube that provides one level of choke for lead shot will shoot the next higher choke pattern with harder steel shot. By that I mean that a modified choke with lead will shoot like Imp. Mod. or full choke with steel shot. The choke tubes that came with my BPS are labeled with the amount of choke they provide with both lead and steel. They say something like "Lead IC/Steel Mod," "Lead Mod./Steel Full)" And I know that the Lead full choke tube warns against using it with steel shot. There are also full and extra full aftermarket waterfoul choke tubes available for all major brands as well.

Mike