Well as far as hardest here in oregon I would have to say big horn sheep cause Oregon onlly gives out like 1-2 tags a year. Plus the terrain would be tough also. But for normal hunting tags I would say Cougar cause they are sneaky and smart. I have lived here all of my life and have only seen the tail of one running into some brush as I cam around a corner before the sun came up. And I only know of two that have been killed by people that I know. And we are supposed to have the highest population of them in my area of the state.