1- Handgun
Glock 34 - I shoot it well enough and since I don't really need to conceal it, I'll take the added sight radius, weight, and "inherent accuracy", also 9mm is pretty common and more "trade-able" unlike (insert exotic, magnum calibre here).
2- Firearm (any gun)
Remington 870 - I love shotguns; pump shotguns don't have many restrictions even here in Canada, so I won't have to build up a secret, illegal, unpinned magazine cache somewhere, just to make it viable for a SHTF scenario. I also love their versatility and the wide availability of different kinds of ammunition for them.
3- Knife (has to be a knife)
ESEE Junglas - Firstly, I will probably actually own one in the near future anyways, but more importantly, it seems like an excellent survival blade. I consider knives to be more tools than weapons, but should the need to use it defensively/offensively arise, it's got a significant amount of reach.
4- Melee (any melee weapon)
SAP gloves - Another issue of "I already own them" but in a doomsday scenario, I won't want to lug around another big, heavy melee weapon on top of all this other crap. Give me a good pair of SAP gloves that can protect my hands, and I'm good to go.
5- Wildcard (any weapon ex: grenade, another gun, chainsaw)
Jeep Wrangler - Because he who fights and runs away (even if it's over rocky terrain), lives to fight another day.