I've had propane and diesel generators, never another propane (LP).

The LP has the lowest amount of BTUs/gallon, has to be transported under pressure, and not everyone has it. If you are going to try and fuel it from 20# gas-grill tanks, get a lot of them.

Gasoline and LP generators are usually built cheap, "throw-away" generators. However, they are also cheap to buy per KVA compared to diesel. Gasoline is easy to find most of the time and easier to transport than LP tanks.

Natural gas is the best, if you're plumbed for it, but of course there is no transportable supply so if you're looking for a natural-disaster type generation, not always reliable.

Diesel is IMO the most reliable and durable, provided you can find and store the fuel. As others have mentioned, you can even mix up your own fuels for it with a little research. Stinkier and more expensive than CNG or LPG generators, but if it's for backup use, not regular use, that's expected anyway.

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Gone to the dark side

- Jeff