Superman, not once, but three times continuing to take the fight to Doomsday after several other heroes have fallen. Superman becomes fully aware of what a powerful threat Doomsday is, strongly suspects Doomsday is powerful enough to kill Superman, yet Superman will not give up trying to stop him. It's easy to think Superman is a hero because he's Nigh Invulnerable and rarely, if ever, in real danger. Here, he proves he's a true hero, willing to risk, and even give, his life in exchange for others.
The League against Doomsday. While he trounces each and everyone of them some of them get some decent blows in.
Wonder Woman takes him on one on one and manages to hold her own, leaving him panting in exhaustion. This being Doomsday however, he quickly recovers and follows up with a CMOA of his own, as he shatters her sword by punching it point-first. Note that, when Wonder Woman throws down with Doomsday in Metropolis, she'd already fought him offscreen with the rest of the Justice League, as she's obviously bloodied and battered before this. And still does better than anyone save Superman himself against the monster.
The Flash also deserves a mention. Being visibly pissed off that his friend Green Lantern has been injured in the fight, he picks up Hawkman's mace and starts mercilessly hitting Doomsday with it from every direction. If it had been any other villain, they would have fallen.
Lex Luthor also deserves an honorable mention for managing to keep Doomsday at bay and inadvertantly helping Superman, as despite his reasons for wanting to stop Doomsday being self-centered. Impressively, he opens the fight with a massive blast from his Shoulder Cannon then follows it up with a brutal beatdown that Doomsday barely got out of with another burst of Heat Vision that turned the tide back in it's favor.
Superman finally entering the battle against Doomsday. The whole League has barely been able to slow him down, Wonder Woman held him off for the longest but even she's been beaten to within an inch of her life. Doomsday picks up Diana's broken sword, preparing to stab her with it, when familiar red beams blast him away. Superman and Doomsday do a mutual Punch Catch, and the force blows out every window on the street. Just the start of showcasing how closely matched Superman and Doomsday are, but also how terrifyingly powerful and utterly destructive they both are.
When Lois thinks Superman is dead for good, she throws a rock at Doomsday and stands her ground refusing to back down even as Doomsday advances towards her, unafraid of dying, her determination is what gives Superman the last bit of energy he needs to finish off Doomsday in a Heroic Sacrifice.