What a foolish thread.
Neither is superior, unless you state a specific purpose/circumstance.
Skirts bring out a more delicate, traditional feminine element, and short shorts are more of an appeal to a "don't you want to fuck me" type of thing.
But some men can find skirts more sexually appealing than shorts(i.e. sluttiness=turn off), so even that's not necessarily true.
And, a girl who doesn't have an awesome figure(not talking about fatness, necessarily; just not one with curves well-emphasized by tight clothing) is going to look a lot more appealing in a skirt than short shorts. it's kind of like how if a girl has huge tits, loose clothing doesnt work as well because it will just drape down and make her look fat(unless she really is fat).
but overall the ultimate solution overall is short, tight skirts.