No one plant or crop will do all things for all people... Climate, rainfall, soils, pest etc all play a role...
However, it is one of the major SHTF crops for me and my family. Over the past several years it has proven reliable. It gorws well for us, in our soils and climate. And on a per foot basis it provides more usable calories than anything else I grow. Roughly 45-50 feet of potatoes, planted in one double row, provided some 500 lbs of spuds. We still have 100 lbs or so left over. That one row provided a full year of potatoes.
I can and do grow other things. However, the potato provides for carbs than most anything else I can grow. I do like another aspect of the lowly spud: Its low tech and low cost. I need no specialized equipment except a shovel. I do not have to dry, freeze, can or otherwise preserve the spuds. I cure em, stack em in baskets and stick em in a cold room. And they provide viable "seed" for next year.
I cannot grow rice. Corn is more susceptible to pest and problems, and far less reliable, for me. It also produced substantially fewer calories. I have not tried wheat or other cereals, but the process of growing, harvesting, threshing, removing chaff, grinding, etc looks to be substantially more work for similar or likely less calories.
The spud is the cornerstone (but by no means the exclusive) crop in our garden...