never heard of aiden or sonata artica, but atreyu is metalcore and system of a down is alternative hard rock. blindside could be considered post hardcore... although when the hardcore genre comes from early punk from the 70s played heavier and faster it makes it sound like blindside is far from that. blindside is a very hard band to define, just like most foreign bands of the sort, but they also have adapted very much from their original style. early blindside may be more post hardcore, but as a whole they are easier to just call a rock band, and it\'s easy to avoid ridicule from die hard fans that way.