For PLO I'd have to go with AAKQ double suited, AAJT double suited, or AKQJ double suited.
I think it's pretty hard to argue the fact that any double suited hand is superior to a hand that's not double suited, as a suited hold 'em hand is superior to it's non-suited counterpart. As for the strength of starting ranks, that's certainly debatable. Of course AAxx is a favorite in Omaha, but nowhere near as far ahead as it is in hold 'em. With so many cards out there, you're highly unlikely to win with only a pair with multi-way action, which you'll often get in PLO (still more in PLO8). That leads to the strength of draws in Omaha. Having KQ with AA ain't bad, because it leaves you drawing pretty live as well as having the high cards, but subbing KQ with TJ leaves you drawing to the nut straight, no matter how you hit it.
Just a few thoughts.