Birdshot is is better than a knife, but you have to be very close. Inside a house, you will be very close.
That said, #1 Buckshot is what I prefer in a defense shotgun. Yes, you need to check patterns and you need to understand the effectiveness, penetrating ability etc.
Doing shooting reconstructions, I can tell you that birdshot inside 10 yards is messy and fatal, but it falls off fast. Buckshot, depending on load, pattern and distance can be effective out past 50 yards. I've looked at some data from real shootings with low recoil buck and while injured, past about 30 yards, it is not fatal with a cylinder choke.