Used King School for my Private 5 years ago and scored in the 90's. Just did the IFR course and it was excellent as well!! The videos and test questions prepared me well to understand the material AND what the test questions would look like. I'm confident I would have passed the test with just doing this. But, like I did on my Private test prep, I reinforced my knowledge by running through another course's test questions. For IFR I ran through the Sheppards Air questions just once. This combo got me into the 90's on the IFR exam. FYI - just doing the Sheppards course would not have prepared me for real life IFR flying. King's videos were great giving a real life application of the concepts and material.
Instrument Rating Ground School & Test Prep