Well, they all basically make the same card. I would go for HIS, because it has good cooling. And IMO, Asus is overpriced most of the time.
Never go with Asus on videocards.
I'm sorry but they just plain suck, overpriced as the poster above said, not to mention the fact that they often misleadingly name their cards.
(my 6800 'gt' actually being a 6800)