When picking a weapon to survive the zombie apocalypse, one must consider what would be the BEST weapon over what would be a good weapon or even the COOLEST weapon. Many factors come into play when choosing a weapon. Storage space in your shelter, the weight and storage space available if you are on the move, how loud said weapon would be etc. Listed below are weapons that pack a punch, and are a mixture of silent weapons and those that are loud.
1) Semi-automatic magazine-fed rifles
Though much debate could be done about the fine-grained specifics regarding individual models, there is no weapon more suitable to a wide variety of situations than an autoloading magazine-fed rifle. Able to be loaded and readied quickly, and capable of providing sustained, accurate fire from arm's length out to standoff ranges at a rate as rapidly as the shooter can comfortably acquire targets, this sort of weapon would prove useful in nearly all survival situations, ranging from hunting and taking small and large game to defending oneself against other humans, and everything in between. Depending on the cartridge chambered, the shooter may also be able to defeat armored targets and light barriers as well.
2) Semi-automatic magazine-fed handguns
Almost as important as a solid long gun is the sidearm that should accompany it. With operating characteristics similar to its larger cousins, a sidearm provides the shooter with an immediately accessible secondary offensive option or reliable defensive choice that maintains a safe distance from the target in the event that their primary firearm runs dry on ammunition, malfunctions, or otherwise fails. Such a weapon can be easily drawn and quickly reloaded, and ensures that barring some extraordinary circumstance, the shooter will always be armed.
Some manner of crossbow would likely be as valuable as any firearm, and would provide a survivor with a means of eliminating single targets with a degree of subtlety not afforded by other ranged weaponry. Aimed in a manner similar to a rifle, crossbows would prove much easier for most individuals to accustom themselves to, especially those who already possess experience in handling long guns. As an added benefit, any ammunition expended could be recovered and reused, provided that it was not damaged by the initial use.
4) Manually-operated shotguns
While not optimal choices compared to most other firearms, due to their relatively limited ammunition capacity, short range compared to rifles, and bulky ammunition, shotguns are an attractive choice provided there are no other alternatives. Though the method of reloading and operating most shotguns can be offputting and difficult for most shooters (since each cartridge must be individually inserted into the weapon's magazine), their reliability and somewhat forgiving patterning of shot at moderate ranges may be serviceable enough to keep someone alive until a better weapon could be acquired. Also not to be overlooked is that most manually-operated shotguns can chamber and fire a wide variety of ammunition types provided that the appropriate size of ammunition is being used.
Though their limited capacity and the relatively complicated method of reloading inherent to most models has relegated revolvers to a practically novel status in most contexts, like shotguns, one would be a welcome addition to the arsenal of someone lacking better options, and - depending on the cartridge the weapon is originally chambered for - may allow for the usage of several different cartridge types.
Melee Weapons Edit
It can easily be seen that a decent melee implement could be a valuable last-ditch defensive tool in the event that all other means are out of reach, or if all ammunition has been expended, or in the case that a single target must be eliminated relatively quietly. They may also be the most viable choice in a case where a survivor simply has no access to firearms.
Unlike most ranged weapons, melee implements are reliant entirely on the physical strength and endurance of the wielder, and are only practically useful in emergencies, as even well-trained individuals in peak physical condition tire very quickly when delivering blows strong enough to destroy the human skull.
1) Machete or similar edged weapon
A machete, while offering nominal utility as a tool for clearing paths through thick vegetation, would offer much greater utility as a weapon. While not the most immediately deadly weapon on the face of things, a heavy, reinforced machete or similar one-handed, bladed melee weapon has the capability of not only killing provided the user can deliver a sharp blow to the head, but can easily disable humanoid attackers, which generally requires less thoroughness and energy. While the ultimate goal in a life-or-death struggle is generally to kill the target, sometimes this may not be optimal, or would require more time or energy than is available, meaning that a simple chop to the legs could render pursuit of the user impossible, as a target without functional legs cannot chase you.
2) Baseball bat, or similar blunt weapon
Baseball bats or other sports equipment of similar construction could represent an easily-accessible and inconspicuous means of defense and attack. It should be remembered, though, that most blunt weapons are not capable of immediate and guaranteed crippling or disabling of a target, and that such a weapon's durability can be greatly determined by the material it's composed of. Even heavy wooden implements can develop cracks after only a relatively few solid impacts and break, while their aluminum counterparts can be just as vulnerable to damage, bending and deforming in short order.
Crowbars offer great utility to a survivor, enabling their user to force doors or destroy their facings, pry open containers, easily shatter most glass, and effect other means of surreptitious entry, but they also represent a decent last-ditch melee option. While not optimal, given their shape and construction, a crowbar could be used as a solid blunt weapon that can be relied upon not to break after a few swings.