Ultimately my evaluation of land being the most worthwhile asset is based on the requirement of survival and unless there is a massive cultural shift that destroys our love of gold (something thousands of years of time have failed to accomplish) then I still foresee gold being worth a lot. However in the immediate aftermath of a financial doomsday, land still seems to be the best commodity to not only stay on your feet, but perhaps to thrive. Once the immediate effects of the doomsday are over, a decade, a century (depends on the rate of recovery), gold will once again be worth a lot.

Honestly, I do think land is ultimately the best commodity to have under the circumstance of complete financial doomsday and indeed most financial circumstances. Ideally land that has a natural source of fresh water, underground or river. It allows you to be self sufficient, at least for your family, providing your own food and water. Perhaps if you're prepared enough you can set up some solar panels to generate a small amount of electricity for yourself, although I'm nowhere near knowledgeable enough on this subject.

Obviously squatters are an issue but if you have excess land than what you and your family needs to live and grow food then you could very well rent out your land, obviously not for money, but some other service, helping out with the farm, defence of land. A feudal agreement of sorts.

Of course if no one respects your property, and are willing to kill you for it, then no commodity is better than any other. Even guns, you're just one person.