I voted Randle. Shepard would need a better demonstrated arm to be #1 at the QB position. (basically same reason as parso and bhelm)
Easily Randle. The #1 recruit is generally someone that is a lock to be a successful player. Shep may have the better career -- but he will have to work harder for it.
I can't remember who on here said there are no sure bets, but damn Randle is as close as it gets if he ain't one. I agree with your assessment wholeheartedly, Randle more the sure bet, but Shepard with unbelievable upside once he has the passing game down.