I would say Kathy S, because a)since she is not advanced, she attracts a much bigger audience of beginners through intermediates. b) I think Kathy has a much bigger variety of workouts--(walking, long slow cardio, interval cardio, weights, belly dancing, yoga, pilates, etc.) c) Because her workouts have historically been available retail, I would guess she has more exposure. She has also written several fitness and diet books. As an almost life long intermediate worker-outer I find Cathe intimidating but Kathy S is familiar and comfortable.