For me it would be one of the carbines since I have 30 round mags and about 2000 rounds of ball ammo. Plenty for the required head shots, controllable, light. I would use my 1911 as the standard backup, though I would prefer to have an XD45 with the 13 round magazine or even some double stack 9mm. Might have to run out and buy that XD this weekend -- just in case

I could outfit a nice party with adequate weapons and ammo.
A second carbine for somebody. A 357 (with 38s) for my wife. Another 357. A Garand for some big guy and I even have plenty of greek 30.06 in bandoleers on clips

A couple of Enfields with about 1000 rounds of reliable Indian 303 from the 1930s and several thousand rounds of marginal ammo that would make life exciting if it came to that. about 400 rounds of 8mm for the Mauser. About 600 for the Mosins. Not exactly run and gun, but a better deal than most parties that are on the run from zombies have handy.
Of course, it would REALLY suck if they were the zombies from the Dawn of the Dead remake.
Charon