Poision has the most range but doesn't always hit even if it should lightings have range as well and always land there hit so id have to say lightning is the best tho i will always favor my poisons
Offence - lightning/poison
Defence - lightning/poison
Raising - fire
Depends on the scenario and how experienced the opposition is. With gas masks equipped a poison is pretty ineffective, however without them people get wrecked.
Fire looks the best and thats the only one i use for now since it's the closest to a "traditional" dragon. Plus i think they are fun but i only play dedi soooo
Like people said it depends on how you use them. I use my poison or lightning or poison for fighting and my fire to go to get milk or kill an alpha wyvern.