I don't normally like "sexy" costumes (mainly for the peculiar reason that I like detailed/crazy outfits a lot more), but
Resonance of Fate really nailed a unique look with "sexy print" outfits... most peculiar is the third party member: A fella with a man-bra.
Also, while it's easy to disapprove of the Tales series charging lots of money on lots of DLC... The Vesperia sets were AMAZING and totally worth it (to me) to drop the coin on.
A Tales villaisn set, a "best armor" set, and the very cool "Namco Set" which shows some love to the Company's other franchises:
Worst goes to the Tales series high school outfits for taking cool costumes and adding a usually horrendous battle theme to it.