I will go with the sniper and unlimited hollow point ammo. Head shots are the only thing that kills them, thats the reason I picked this gun. Also I love the sniper.
I'd take my AR and find a nice high, hard to get to place and just start picking them off. Though I would love a Steyr, only really seen them either in Ireland or the sporting goods store but their nice rifles. AK's jam just like anything else and shotguns aren't good for long range, which is what you want. I'd take a knife for backup, but lets face it, it takes a lot of strength and endurance to use any melee weapon for any amount of time and the zombies are in no rush.
One powerful sniper rifle and another kinda of powerful but is semi-auto.
I'd find maybe a really tall tower and just sniper. I'd have a knife with me and a stack full of grenades to throw down. If they manage to get up.. I always have a zip line to the next building ;]
Shortbusses (which are not "lanes, trains, or cars" and therefore are okay) are the best weapon against zombies. Afterall, zombies crave brains, and therefore would avoid the short bus. A Redsox baseball cap is also a powerful deterent. jk jk...