I know the Stranger has had some low end showings but whenever the Cosmics gathered we always saw him grouped with the likes of Galactus, Kronos, grandmaster and the Watcher. I think it's safe to assume these types were his peers...but maybe I'm wrong.
In the "What if" (I know I know) with Korvac he's tossing around Planets... I just dont see Zues being able to rub shoulders with the aforementioned entities..Odin Maybe...
Molecule Man- Isn't he at least as powerful as a sentient fully formed cosmic cube? On the high end wasn't he capable of tossing Celestials around? I would think he is easily on another level.
and i do not think that Stranger quite measure up, for most of his appearances, despite showing up with the other cosmic characters.
It is more of a pedigree issue than measure of power. Stranger has had more problems with Surfer and Thor, than Pluto/Hades necessarily had. And Zeus was always more powerful than he was, save the Ares mini, where for some reason, Zeus was weakened.