I may be way off base here, but it is my gut reaction that if SD were to make Brink as “good” as W:ET, it would sell about as well, maybe slightly better than W:ET. By making it a game that can appeal to the average player, and where the average player, despite lacking the twitch skills of the expert/pro’s can find success, then Brink will sell much better and appeal to many more players.
So in the end the question of which is the better game is a purely subjective one, but the right answer could mean a great difference in mass appeal.

