Lucifer. Sise-Neg eventually became supremely powerful, to be sure, but absorbing universal powers has it's limit.. Lucifer and Michael operate on a divine power, allowing them to create the kinds of powers Sise-Neg absorbed.
Parallax became all powerful in a similar kind of way.. He started with the Oan power battery, and than took in chronal energy and started bleeding away the universe and all it's dimensions and material to remake it. I can't see Sise-Neg being too much above that level...