According to who? In the words of Demi Moore, I strenuously object. Of those seven quarterbacks you've listed, he is probably a better prospect than Smith (who was drafted because he was an easy sign) and maybe Cutler. Eli was the hands down number one pick, and whether is was because of his name or his game, he was a much stronger prospect than Ryan. In hindsight, it's easy to say Aaron Rodgers, but if he were willing to sign for what Smith did, he would have likely been the #1, as the Cal offensive system was (at the time) considered a good one for NFL development. Ryan a better prospect than Quinn? Short memory. This is the weakest QB draft since 2005 (Alex Smith). If Ryan was in last year's draft, I seriously doubt he's in the first round. If he was in the 2006 draft, I doubt he goes in the first two rounds.
That said, I do think he's the best QB prospect in this draft by a good margin.