Trench spike/knife. Best zombie defense weapon there is.
I've read the zombie survival guide a few times:
It is praised as "the best compact anti-zombie weapon on earth".
With a non-serrated edge, the blade allows you to easily slide it through the skull of the undead, destroying its brain. The brass knuckles provide more defense with the ability to crack a zombies spine with a swift blow to the neck, severing the brain from the body.
Although, having a 9mm pistol would be a suitable weapon to use as well, and keep the trench knife for back up. Having an assult rifle weighs you down eventually, and ammo is easier to come by for a pistol. It can get you out of tight situations and be stored/carried easily. Besides, the only time you would want to have to fire your weapon is when you absolutely have to. The last thing you want to do is attract loads of attention with the sound of gunfire.
Loadout:
-9mm Pistol
-Trench knife
-Pry bar