The main reason I lean towards Amari is his technical prowess and body control when running routes. ESPN once did a segment on Kiffen's sideline TD gestures--they showed two plays, with two Bama receivers running a corner-post route.
Both went for TDs--one was to either ArDarius Stewart or Deandrew White--when that player faked the corner cut, the whole body twitched. Effective, but it clearly at the cost of some speed.
When Amari made his fake, he just twitched his head--and when the corner bit on the cut, Amari was past him before the poor schmuck even knew what had happened.