Sersi is strong enough to fight against Exodus, but she lost quite fast.
Exodus himself said Thena is weaker than himself, but she's almost at his level.
Druig fought half a dozen X-Men led by Cyclops around Civil War I (I think he lost).
Ikaris and Blackbolt fought as equals, but Blackbolt didn't use his voice.
The Forgotten One is roughly Hercules level.
Zuras fought Zeus himself once.
I don't think your average named Eternal is the equivalent to more than one Omega. Storm would be quite vulnerable to a quick strike from an Eternal, lacking force fields or invulnerability, but Magneto, Exodus or Jean can give most Eternals a really bad time...