Its hard to properly answer this.
Naturally, many of us think that our favourite AP mid is the 'best' (Ocelote for me) but i admit that a large amount of my admiration for him comes from his passion and innovation, instead of pure robotic mechanical skill/APM.
Perhaps you ought to refine your question i.e. give us a better understanding of what you mean by 'best' because thats an awfully broad concept.
- without so much as a break in stride.