Rachael's hair kills her for me. Her body's fine, but her hair and unfitting Excella like bust while in a wet suit makes her design pretty tasteless.
Jessica isn't bad, but her wetsuit outfit is awful and her FCC and winter wear outfits are hit and miss.
No complaint on Jill, besides maybe her casual attire from 3. She pulls off her battle suit and BSAA outfit very well in 5.
Ada beats everyone when it comes to fashion sense and beauty, though. Her outfits tend to be ridiculous, but they look outrageously good on her. She looked stunning in Darkside Chronicles. Her legs are awesome.