Exitar just because I like him more the full power of the Celestials expecially Exitar has never been Explained I heard that Galactus would one day become a Celestial. I also heard the same about Franklin Richards I think people understimate there power for instance they stop Ego once before from battling this other Cosmic being and then they destroyed it. I believe there purpose in Marvel Universe is high up and I also remember the amazment that Galactus when HOTU Thanos absorbed them thats saying alot I think.
And
http://en.wikipedia.org/wiki/Dominus_%28DC_Comics%29
He's discribed as being "all-powerful".
Eternity > Celestials
Kismet = Eternity
Dominus > Kismet