I don't really know anyone beats Saint of Killers. He is an immortal cowboy who shrugs off nuclear bombs armed with guns that never miss. He literally murdered god and all of hell. I really don't know even Thanos has got anything that stands up to that.
Saint will destroy them all his gun can kill anything in creation and he cant be killed by anything.
Actually Spawn is the only guy here it can't kill hence why I put Spawn first. SOK's revolvers are the ultimate killing devices they can take life from anything including gods etc..... however they are useless against creature's who's life has already been reaped (undead characters). We saw the guns fail to kill an undead being in Preacher because it was already dead. Spawn is the only undead character here. All the others are living beings who transcend death so they can be killed by the revolvers. Spawn on the other hand cannot as he is truly undead. The revolvers will be about as useful as normal revolvers against Spawn and since he has better feats than SOK minus his haxed weapons then Spawn should take the win. Unless this is Throned SOK in which case he stomps them all easily.