Without a doubt, Valgarv loathes the golden ryuzoku. He possibly hates them more than he hates the mazoku because it was the goldens who were the ones responsible for the slaughtering of his people.

During the Kouma War, the golden ryuzoku asked the ancient ryuzoku for their help. However, being a peaceful race and wanting no part in the war, the ancients declined. They would stay neutral. However, this didn't go over well with the goldens. They knew how powerful the ancients were and became enraged that they wouldn't use their strength to fight. More-over, they were afraid. So scared, they jumped to the conclusion that if the ancients didn't help them, there'd be a possibility that sometime in the future, the ancients may turn on them.

What scared the golden ryuzoku the most was the fact that they may lose their place as the most powerful of the ryuzoku. They knew that the ancients held the most powerful weapon -- Galveria the Bow -- and they wanted it for themselves to ensure their place at the top of the food chain. Their solution for this fear? Genocide. Orders were given to the goldens to slaughter the entire race of ancient ryuzoku. Every last one of them -- men, women, children, eggs -- were to die. All because the goldens were too selfish and power-hungry.

This act of pure selfishness, to Valgarv, was no better than what the mazoku would do -- if they can't have it their way, kill whatever is stopping them. Valgarv finds it utterly disgusting that the golden ryuzoku took it into their own hands to play god and take the lives of so many innocents. It's the fault of the goldens that Valgarv's life was ruined, that his friends and family were senselessly murdered. He can't forgive them for their sins.

What's worse is that the goldens tried to make it so that the ancient ryuzoku were the bad guys. Not only was it bad enough that they killed them but trying to shirk the blame is just too much for Valgarv.