Water, because I would have control over two forms of matter. That is to say, I could use ice (shields, swords, and so on) and the basic water (water blasts, bubbles, etc.). Also, Zina, why does soul use electricity? Is it just that you wanted to use soul as an element but needed something to use and couldn't think of anything else, or is this deeper than it seems?
If all the worlds a stage, then I get the lingering suspicion that I'm just a stage hand.