Porsche recommends Mobil 1 0W-40 or 5W-40.
RedLine, Motul, Amzoil, Royal Purple are all good oils and each has it's faithful, with plenty of documentation to back them up.
Are any of them the BEST? Depends on who you ask - there's no shortage of varying opinions.
Which is the best oil?
That which is changed regularly between 7500-10,000 mi., or at least annually.
Do that, using any of the oils listed above, and you're not at all likely to have any oil related problems for the life of the car.