I would go with Hartline as well. He is rookie Tannerhill's favorite target. Seeing as how this is Tannehill's first season, Im thinking, that he will stick with what works instead of trying to hit every reciever he has. Only problem for Hartline, as I see it, would be, if he gets double covered, which I highly doubt he will be at this stage of the season.
In short: Hartline