No, absolutely not. That distinction still belongs to MK64. For it's time, it was mindblowing, just as much as MK8 is now (graphically). And even now, even with dated graphics, it still has great tracks, perfect controls, great balance that no other MK game has had since, and THE best battle mode of any of the MK series.
MK8 is a very good game. WITH a real, legit, decent battle mode, it could have been great. But Nintendo got lazy on that mark, so it loses points for that. It has to. With all that disc space, they also don't have much reason not to have included some kind of "mission mode" like DS had, thought that's a minor quibble. Bottom line, MK8 is a great release, the best MK in a long time. But no, it's not the best MK ever.