Two video cards will fit inside the Antec Nine Hundred case. Some of the newer video cards are about 10.5 inches long. You may have to reposition the hard drive cage to make room the extra long video cards. Not a big deal.
I have not seen any sales figure but from articles, reviews, a forum posts it appears as if the Antec 900 is one of the most popular cases with gamers. There is a new version of the case: