Ahab you sure it was Russ, Sang, and Angron? I recall sang, and Russ, but I'm pretty sure the third Horus mentioned was not Angron. Particularly because when I read it was taken back for a moment that angron wasn't one of the three mentioned.
As for Ravens flight audio book, Corax states that he is a lord of war, but angron is war incarnate. Additionally he muses to himself that if he were to fight Angron in that setting he would be killed in all likelihood, and that he believes only Horus would be able to best him in combat, and perhaps Sang.
But you have to keep in mind, each of the primarchs had their own opinion on who the top fighters were, such as Horus viewing Russ, Sang, and (pretty sure it was not angron mentioned) corax.
However lets say Corax is superior to Horus in combat, this does not mean that Angron is not superior to Corax, it could simply be that Corax is better suited in taking down Horus's fighting style and strengths. And even though Horus is more likely to lose versus corax, he could be more likely to win versus angron, due to match up of tactics, strengths and weaknesses.
Last edited by Lux; 10-31-10 at 04:12 AM.