It seems that the holy grail of cooking fuels on a boat, according to most cruisers, is propane! It can be fed into a stove/oven that is gymbaled, allowing you to cook effortlessly while underway and bake dinner evenly without fear of burning anything. Propane is a favorite as it burns cleanly and lights instantly.
The problems with propane are the cost of filling your tanks, the methods to store it, and any leaks it might have in your boat.
Propane sinks, so if it leaks out of its tank or any of the lines to the stove, it could potentially sink into the bilge. The next spark that occurs will blow the boat to splinters! To avoid this, propane is always stored in lockers that have a drain overboard and no communication with the rest of the boat. This lets any fumes vent overboard and away from the bilge.
Propane is stored typically in metal cans, and metal on an ocean going yacht is going to rust! They do make composite tanks that are impervious to rust, but many filling stations do not trust them and will not fill your tank.
Aside from storing the propane, you also need to worry about getting it into your tank! Sadly, the valves used on the tanks are not universal, so if you plan on doing international cruising, you might find it difficult to get the station to adapt to your valve and fill your tank.
Lastly, there is typically an electronic solenoid that cuts off the fuel flow of propane to the stove. You need to have a manual way of bypassing this solenoid so that if the solenoid were to fail, you will still have the ability to cook and eat well while cruising.
Propane has its drawbacks, but luckily it seems to be such a popular fuel that everyone has it and has worked the kinks out of the system. This means that someone in your anchorage will probably know how to repair the system and have parts that you might be missing to get your cooking going again.