If you only make one earth works better for a dom since many of electric's powers don't benefit from domination as much and earth's defense debuffs with the option to add achilles heel -resistance benefit a dom's attacks. That's not to say electric isn't great on a dom too but it can just as easily be a controller - time or poison with their melee auras combine well with the one in electric. Should ask on the forums of the server you're playing on, though, as there will be more folks to give opinions there.