What weapon choices are good depends a lot on what Jon throws at us. Normally there's a ton of regular zombies. As you might figure, guns aren't great at killing zombies... unless you blow their head off. Problem is... none of us are great at doing that.
If your goal is to slaughter endless amounts of normal zombies, dual wield swords. You'll DEFINITELY kill a ton of them....
...But there's going to be more than just zombies. And sometimes the "big guns" are required to deal with that stuff. Sometimes doors need giant holes in them. Sometimes barrels NEED to blow up to save our asses. Sometimes giant zombie ogres show up and eat the sword wielders. Swords can't really work well on that sort of stuff unless you're looking to die for the cause, and people WILL die for the cause (by choice or not).
If you want the highest kill count, go with two swords. If you want to be forced to get creative, do something else. It's going to be fun no matter what.
I will be using a heavy stubber. Hopefully I don't run out of ammo in the first few rounds as usual. Although the barrel of the gun makes a decent club.
(Seriously though, we're gonna need people with two swords. They shred zombies, tank, and kill for the rest of us when we're trying to figure out WTF to do so we can make it out alive... which most of us fail to do anyway.)