It also depends on the threat. One guy or four, one guy possibly then 1911 with eight rounds might be enough. But the fact is you don't how many and what they will be armed with. Take here for example if terrorists are coming to your house for your guns or for you they came well armed ak 47 ect and in numbers.
So what would i rather have a 9mm cz with 19 rds or a 1911 with 8 rds i think the answer is obvious.