Well they're totally different. One's supernatural and the other's about a group of psychopaths. Both are scary in their own way. The Haunted makes you fear the unknown and opens our eyes to the other side(the darker spiritual side that is), and Last House on the Left scares you by showing disturbing imagery that unfortunately happens enough in our world.
Depending on your views and beliefs of the spiritual world Last House on the Left may be a more realistically intense to some, more then The Haunted.