It depends do you mean without sustaining injury( being cut with a knife, shot with a gun.. etc) or being able to keep fighting while taking damage(ie getting hit by incredibly strong people but being able to take it and keep going, getting cut but not being put down by it, ...).
If it's a test of pure invulnerability:
Superman
Silver Surfer
Hal Jordan
Thor
Hulk
If it's pure damage soak:
Thor
Hulk
Superman
Silver Surfer
Hal Jordan
In that scenario I'm probably going with Surfer actually. His cosmic glaze does give him a nice indestructible body already and he can summon shields.
Superman is next, although if Thor is going plum knockers and is in his say thee nay, break every bone in my body and I'll still get up, mode he may be able to outlast him.
Ummmm Hal Jordan is good but GLs shields are often faulty against pure bricks that simply smash through them. It happens surprisingly often, more than it should.
even though Surfer is perhaps at base more durable than Superman, I'd put Superman ahead of Surfer just because it seems Superman can will himself to reach an extra level in the most dire situations
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Hate to sound like a Marvel fanboy, but I'm going with Surfer to take first place and Hulk to take second in this competition.
No one else would last nearly as long. Reason being: H/P DD had poisoneous bone-claws that would have killed Superman had he not had his Motherbox to heal him. Hal's shields would get shattered easily, and neither Thor nor Diana or Superman has the durability to last against him. We are talking about the same guy who KO'd Darkseid in probably under a minute's time.
Surfer and Hulk are immune to poison. Surfer's not only got insane durability (like Supes), but shielding as well. And Hulk has an outrageous healing factor and is just going to get stronger and heal quicker the longer the match lasts.