Superman held a black hold, benched the weight of the earth, and shattered a planet to pieces on two occasions, and as you see above cracked the surface of a planet from collateral damage, which is also something he did in a battle with General Zod when not pulling his punches with Doomsday inside Metropolis.
Superman has moved so fast his molecules became intangible against a stronger Doomsday, Superman cracked a faulty Doomsday Clone's face open and HVd a thousand such Doomsday Clones, flew Darkseid to the sun faster than light, has time traveled due to his speed several times, has survived the destruction of a sun eater which possible generated more heat than a super nova with red sun radiation, he has accelerated to speeds allowing him to escape a black hole that had sunk through two dimensions because of it's supermass....etc etc.
I think his speed culminated with his strength and durability more than surpasses the force of the Mjolnir when wielded to maximum effect by Thor.
Thor's only stronger attack is the Godblast, which does possess more energy overall than Superman's strongest blast of HV, but HV is fired more quickly, can be spread out or focused, not wasting energy on the sorrounding area like the Godblast...HV is far more versatile if less powerful, range, speed, focused damage...etc etc.
Superman is the Alpha and the Omega of High Heralds in Comic Dom...the first and most powerful...at least in my opinion he is.