If I had to rank them it would be probably WHL being the best, then OHL, then QMJHL. But great players come from all three.
Just listening to Nolan Patrick last night -- he already sounds like a Devil talking about defensive responsibility and playing as a two-way center. I think they will take him. He's a big, talented guy up the middle, and he will take less time to adjust to living and playing hockey in the United States (presumably).
He's also from the same hometown as Zajac! And he played junior hockey with John Quenneville last year. So the Devils should be familiar with him.