Which flier?

Ahead of week 1. I drafted Michael Pittman with my last pick to see if he can stick as a flier.

Malcom Brown, Josh Kelley, Justin Jackson, and Parris Cambell are all sitting on waivers.

Which is the best player for me to have on my bench going into the season either as a late round sleeper that I can eventually start or as trade bait for the league?