I think Stoner was supremely talented, but lacked the drive MM has. If Casey had that drive he would have hung around longer than he did. MM has a drive to win that CS never had. Don't get me wrong, Stoner had immense talent, but he never utilized it fully. He has two titles to show for it, but always felt he left titles on the table.
I rank MM higher than CS at this point which is no small feat. But at this point MM is clearly the superior rider. He forced Lorenzo and Rossi into crashing out in 2016 at Motegi, then did the same think to Dovizioso in 2018. He doesn't have a superior bike, but he makes it work for him. Makes me wonder how Lorenzo is going to do on that bike since it's less stable than the Desmosedici. He may take well to it, or he may take time to gell with it. I don't think MM has any fear of having Lorenzo in the garage with him.