insulate concrete wall above grade?
I will try to make this simple. hot air moves to the cold air. So in one season the air moves into the house and the other season it moves out. The only way to make this work is an air barrier that is not effected by moisture. So the answer is 2' form board or closed cell spray foam. In your area I would recommend a minimum of 4" Anything else you use will fail eventually. Also be sure to completely seal the joist space along the entire basement at the rim band. This is critical since the dew point is reached easily at that juncture and water condenses on the rim band and soaks into the floor plate and good bye house. The foam air seals and insulates. Nothing else will work as well...period!