Captain Atom is in that vague top tier range. Physically he's below Wonder Woman and Superman, but in terms of his blasts and radiation he should be closer to the top for earth heroes.
Solomon Grundy is more mid level in the comics especially when he tangles with Batman. The Justice League cartoon portrayed him closer to the Hulk's level
I wouldn't worry about that too much power levels tend to be vague and often fluctuate in the service of a story, especially in a shared universe.