Having digested the designs for a little time, I actually like them both. I think the XBSX slightly takes it.
PS5:
Pros: Slick design, love the LEDs and the vent.
Cons: Only in white and too tall.
XBSX:
Pros: Love the vent on the top, the width, and how the CD drive is flush.
Cons: Design is just a little on the 'safe and unimaginative' side.
XBSS: The less said the better.