Pre-DotNG Source was implied to be on a higher level than Eternity, IMO.
DotNG didn't necessarily show the Source to be weaker than previously implied (after all Darkseid's power was multiplied by several hundred thousand orders of magnitude), but it certainly established limitations for the Source (e.g. lack of true omniscience, lack of true omnipotence, character failures, etc).
so, IMO..
Pre-DotNG Source >>> Eternity
DotNG Source => Eternity