Net or Org!?

So everybody knows that first you pick the .com and then in case of unavailability you go for a .net or .org.
Personally I've always had the .net as my second choice, but I see that many people around here prefer the .org.
As far as someone can say with some certainty those two work the same on the eyes of google, right? Or have you been proven different already?
Let's scratch this subject a little bit and see if we get somewhere.
Which one you prefer or for a fact know it's better and why?