The best firearm would probably be any assault rifle you can get your hands on. It would be a mistake to suggest a shotgun. Shotshells are a lot larger and heavier than normal assault rifle rounds, much shorter range, and a shotgun cannot be fired nearly as fast as a magazine-loaded rifle. AR15 / AK47 would be the best choice, although any rifle with significant magazine capacity 15+ rounds could work fine.
The combination of gasoline and a flare gun has been noted to work when the zombies are in tight groups and you have adequate time to prep and escape.
The best hand-to-hand piece is probably a titanium pry bar. Lightweight and good for brain-shots. A machete would be okay, but has to be kept extremely sharp at all times to be effective.