So, which would be better, water, air or earth?
In order to make an intelligent measurement of value, you are going to need to provide some sort of framework for what you mean by better.
Better, as in, more fun? You will likely have to determine this yourself, depending on what you find most enjoyable: throwing mud on someone, spraying them down with a hose, or blowing on a baby's face so it makes funny faces.
Better, as in, more powerful? Traditionally, the most powerful gods were lords of the Sky, but its kind of hard for those three elements to fight each other anyway.
Better, as in, most morally upright? They are all pagan infidel idols, and are all equally sinful
@dldnjstjr: In the interests of creativity, and relative initial player parity, I protest using existing gods.