Never really knew about Horde Prime until a few years ago. Guess I missed those episodes back in the 80s.
Hordak works even though he shouldn't. Skeletor is a simple concept. Death, with magic and purple. And he's funny, too so bonus points, right? How can you top that by having some guy who can turn into different things and controls an army? On paper it doesn't work.
But in execution, somehow it does. I won't say one is better than the other. They're equal, which is such a strange thing. Both are funny, menacing and driven, just for different reasons. They compliment each other.
She-Ra, on the other hand, just totally kicks He-Man's furry underpants. She rules, he's boring.