Realistically, a bolt-action rifle would be the best thing to use in case of a zombie attack.
They are accurate, and require time for each shot. Making it so that each shot counts. But a semi-automatic rifle would be better, probably, for essentially the same reasons.
Dont' know why I didn't pick that one.
Pistols are bad because if there are zombies about you'd be scared out of your mind. It'd be pretty hard to aim accuratley.
All of those other ones are great for killing humans, but zombies don't particularley need their organs. A shotgun would shread them to bits, but if the brain isn't destroyed, they can still be hazzardous.
And a flame thrower is much less potent than you think it would be.
Instead of ravenous zombies shambelling towards you, you now have ravenous zombies shambelling towards you on fire.