My preference is any of several varieties of alcohol and a Trangia stove. there are numerous alternative stoves available, some of which are cheaper, lighter, and faster. My Trangia will bring 500 ml of water to a boil in somewhere around 4 to 5 minutes.

Even faster are any of a growing number of cartridge stoves, typically burning some type of isobutane. Boil times are usually four minutes or less. The gas containers store safely with minimal precautions.