They're a people, although only a few left. They need actual personalities that flow and change depending on the situation. New Aatrox, has actually one of the best variation of emotions I've seen yet in a champion, something I haven't seen since Dawngate ~~I miss you Mina~~. His solemness when his quote towards Voidsent plays, his anger that arrises when confronting his most insulting defeat yet: A little girl.
He's a Warrior, who lives to fight and kill. That alone dictates a personality that is much more aggressive. Old Aatrox's VO worked when he was a Force of Nature, 'a living embodiment of war itself', but Aatrox isn't that anymore. He has ups and downs, a personality. If you're going to hate the new VO, don't hate the voice lines themselves. Hate the fact that Darkin are an actual race now, and have had changes made to emphasize that.