Sentry is essentially everything Superman is and more. He possesses insane levels of superhuman strength, durability and speed, as well as a whole host of esoteric powers and abilities that make him more versatile in his offence and much harder to kill.
Regarding his strength, he has done things like lifted a Celestial (a massive humanoid cosmic being), he has torn Ares in half (Ares being a demigod-like being on the level of Thor and Hercules), he has torn through the Crimson Bands of Cyttorak (something Hulk can’t do) and he has stopped a swing of Terrax’s axe, casually, with one hand (Terrax’s axe blows have cracked planets in two), which is also an insane durability feat. He is every bit as strong as Superman.
Durability-wise – in addition to the aforementioned Terrax feat – he has taken multiple blows from an angry World War Hulk (which, honestly, was a poorly-written Sentry, as he should be destroying someone like Hulk with his esoteric abilities) and was merely bloodied by a punch from Blue Marvel, who has destroyed moons with similar blows. He is every bit as durable as Superman.
However, if indeed Sentry was destroyed by Superman, the fact is he would come back. He has died several times only to return immediately – most impressively when the Molecule Man (someone who could easily beat Superman) tore him apart at a molecular level. Sentry simply reformed and did exactly the same back to him using his transmutation powers. He could essentially rip up Superman molecule by molecule (there’s also the chance that Sentry being sufficiently angered could bring out The Void – and Superman wouldn’t want that).
Sentry’s most impressive feat is arguably when he was in the microverse (a universe where everything is shrunk to atom-size). Such was the power-level of an energy flare he created, it could be seen from the normal universe – that’s an insane level of power and it destroyed planets while he was in there.
He also possesses telepathy and, while that’s not his most impressive power (he did cause the whole world to forget him, however), he could still get into Superman’s head.