How strong is Z?

I'm very curious about Z's powers. We already know that he was a former marine admiral and that he is the strongest enemy the strawhats have faced. But exactly how much stronger is than the other main villains, like Crocodile, Moria or Lucci. I just saw a new trailer where he effortlessly defeats Kizaru and T got pretty excited because there aren't many people stronger than kizaru. I want your opinion about his true power. Could he be a devil fruit user or maybe have another ability? I also want your opinion about dyna stone.What kind of power has it got and what kind of power does it give to Z?