Swanky-Tuna
Post-Crisis Balki
Anyways, I guess I would place them as such:
DeathStroke
Batman
Spiderman
Wolverine
Black panther
We know Deathstroke carries all sorts of murder devices, that's a given. Boom = death.
Batman, I'm not so sure about. He doesn't normally kill but I'm sure he has weapons to fight the beefier foes but I'm not sure how much of it he normally carries.
Spiderman has the webbing he can use to hurl objects/people around.
Wolverine has his nice long claws so he can score a lot of one hit kills and is naturally faster than he should be.
Black Panther I'm very fuzzy on. I know he has an energy knife and his hand claws but I'm not sure what else he usually has for offense. I just think a lot of people would survive past the 5 minute mark after getting tagged but then die of bleeding or whatever.
Now if the killing went on longer, I think Deathstroke and Batman would use their edge to Spiderman, at least, as they run out of weapons to throw. And Black Panther would move up because of his speed and more time for his guys to die.