The problem with ANY bladed weapon is it has a good chance at some point in getting stuck in the skull of the Z. I'm not saying they arent viable. I'm just saying have plenty of back ups and don't get too attached to the one your using. You will have to be willing to drop it once that happens or you risk the chance of getting mobbed. I prefer the blunt object my self, hell even a long pole may not be to bad in certain situations you dont have to kill every Z you see just get him out of the way so you can keep going. Remeber fighting takes alot of energy and energy takes food, something that may be scarce.
I would have to say the good old fashion Machete. Guns make too much noise, which could draw the attention of more zombies, same for a chainsaw. Throwing stars and knives, well the skill level is a bit high for most people and besides, what are you going to do when you run out? Besides a Machete my next weapon would be a long Bo staff. That way it gives me an extra 5 to 6 feet between me and the hungry dead.
hmmmm,a katana isn't meant for decapitation though,its meant for death by bleeding,not very useful.....if you had a choice of several weapons,the best all round weapon would have to be the crowbar.this is my personal selection.its perfect hooked edge can easily smash a skull (it worked on a freshly dead cow skull,why not a corpse?)and can be used to open crates and break latches(never shoot them,that only works in the movies!the bounce back)however,gun wise,it depends on the situation.up close,a good ol smith and Weston magnum would be preferred,at a distance of 20-40 yards,a shotgun loaded with slugs(with the bbs it would have to be closer) and at anything longer a nice scoped rifle would be perfect.
the chainsaw,though,naw,not a good idea.itd work beuifully,but you gotta think about the flying blood and gore.one drop in your mouth or eyes and it over.....
bate would be good,for a while.wodden over aluminum though,id last longer......
teh suit shown below,its cool,and would be great,but,uh,were teh hell would you find one!! XD at best,im thinking a cheaper quiker easier to find suit would be riot gear......
Im sorry to break it to you but police forces, the military, and security forces do use shotguns for door breaching. A 12 g slug will absolutely tear a lock or latch apart.