At 2/100 sec evaluation speed for Continuous Autofocus, the Sony a6400 has the fastest responding autofocus currently on the market. It shoots ten frames per second, with the new AI Tracking. However, getting to the tracking is quite an ordeal, which I will explain here.
First if looks for the eye-ball, then the face, then the object or person. And coming soon – ANIMAL EYE-AF. The a6400, at under $900 is an amazing deal.