In terms of elements of the periodic table, i would choose oxygen. it is , if not among them, then the moost bountiful element in the world. i know for a fact that it takes up 50% of the lithosphere, and logically around 33% of the aquasphere, 25% of the biosphere, and 25% of the stratosphere (dont quote me on this, these are just what i vaguely remember from science). plus, i can suffocate people at will
in terms of what you selected as elements though, darkness. darkness > light because darkness always gets to the destination first. besides that they are basically the same thing