I've been through quite a few hurricanes with power outages following. Twice the power was out for over a week. I also work entities that require emergency power.

For most locations we found that natural gas was the best choice. None of the locations has ever lost gas pressure and you don't have to worry about the fuel storage problems. For locations away from a reliable gas supply we would go with propane. For locations that use the generator regularly (enough so that the fuel is not stored for long periods of time) we would use diesel.