Diesel/Gasoline are also very viable. The issue with both is fuel storage. Gasoline oxidizes and gains water over time. Use it or lose it kind of thing.. and how does one dispose of hundreds of gallons of stale gasoline. Diesel is far more stable but grows algae - this too is a maintenance nightmare for a stagnant tank that is rarely used. Even weekly exercise is not enough to keep stocks fresh and replenished. That is another issue. Constant top-offs (exercise uses fuel) so that when disaster does hit, you are full.
Just things to consider....
I store 25 Gallons in 5 Gallon Drums, that I dump into my car every year and fill with fresh premium.
Additionally, I always fill all 3 cars before major storm, just in case.