To be honest, the best weapon in the event of zombie invasion is your brain.

I'm not joking. Since most Zombies in the mythology are dumber than a box of rocks, you'd be hard pressed to fail at finding ways to stop them from eating your tasty brains.
Baring my brain, I wouldn't mind access to the AA-12.
The world's first truly automatic shotgun. What zombie can shrug off that much power? A zombie Cyberdemon? That's what the Fatman is for.

http://en.wikipedia.org/wiki/Atchisson_Assault_Shotgun
Also, as backup I would use an MM-1 grenade Launcher.
Those aren't too hard to find, and in the event of a zombie apocaylse, I'm sure Police departments won't have people there to complain about you stealing their MM-1s.
Yes, I know, they only use tear gas in them, but still, finding the exploding ones aren't that hard. Military supply base.
I don't know, those are the weapons I would use.
I would also team up with the survivors. Especially if one of them was Jeri Ryan. :hubbahubba: Or Allison Mack...

And there are always survivors.
Now, if someone wants to give me the 25mm dismounted AA gun from FOOK 2, I won't complain.

What human rights violations for firing an Anti-air weapon at people?

And Terasha, thank you so much for that link, I used to watch that movie all the times on USA. Now I finally know the name of it!