Ya those three still have a little to prove before you can call them that. There is a lot of potenial there, they are all young, fast and physical and if Carr has time to throw they may not need a running game.
As for the best trio I would have to second the motion that Pitt has the the best Randle el really impressed last year. He is as good or better than any thrid WR in the league. Burress and Ward speak for themselves