Propane is probably the most versatile and accessible form of fuel. You have probably seen the 20 lb bottles often called the "barbeque tank." And you are probably familiar with the 1 lb portable bottles. These two types of containers attach to literally hundreds of stoves, lanterns, and heaters. For short-term emergency equipment, you can see here a typical camp stove, this wonderful Camp Chef oven, a lantern, and my favorite volcano stove.
The problem with propane for a long-term emergency fuel is that it must be stored under pressure, and most of us simply do not have the ability to store large quantities of propane. For this reason, I don't consider it my primary long-term emergency fuel.