I have to agree with Hordesman. Skeletor always seemed to be fighting an uphill battle on a smaller scale, while Hordak had a large and established force at his disposal. Hordak's technological advantage was formidable, while Skeletor's magical ability allowed him to hold his own against He-Man and the Masters.
I think Hordak relied more on his forces to do the work for him, while Skeletor was forced to be more hands-on. My vote is for both, but you have to admire Skeletor's resilience.