I have both and feel the King course is far more detailed and useful. It is a bit "cheesy" with the outdated green screen, and some of Martha's little laughs grate on the nerves after a while, but most of the info you need is there to pass the written, which I can't say for Sporty's.
The one thing I disliked with King is that you had to constantly thumb through the manual to find the charts and illustrations they were covering. Why couldn't they put them in order?!
I do like the Sporty's course, as it is better produced, easier to watch and has Richard Collins offering his words of wisdom, but would recommend it only as a supplement to the King course or to an actual ground school.