I'm one who prefers the longer length. I'm 5'6", and most shorts tend to hit right where my thighs are the "meatiest", thus causing a really nasty case of sausage legs...sigh. Shorts that fall about an inch above my knee, seem to have a more "smoothing" effect and don't look quite as bad. With all that said, I have "chubby" knees with lots of flab in that area...so there really isn't one short (that I've found yet) that will ever make my legs look sleek and strong.
2012 Seven Axiom SL - Specialized Ruby SL 155