The six titles is definitely what separates him but say hypothetically Lebron ends up going 6-4 and has 10 finals appearances with also six titles to his credit. He could have a case of taking teams that shouldn't have been in the Finals to the Finals when in the years MJ didn't get to the Finals it doesn't hurt him because he didn't lose in the Finals. I think if that were to happen there would be some serious discussions.
That would tie him with Kareem. Still not GOAT.