Birdshot is for birds or for making slugs. IMHO
I prefer slugs, one projectile I am accountable for as opposed to multiple projectiles. Besides in my house, buck will not have time to spread prior to hitting an intruder.
There is no one answer. It is dependent on personal preference, home layout, neighbor location, windows, here will misses/pass throughs go, proficiency, etc. Many things should be taken into consideration when deciding.