The maxim I have always used for the draft is that teams without a franchise quarterback need to find one.
In 2013, that may be difficult, as many teams look like they lack the caliber of passer needed to take the next step as a franchise, while there aren't many of those passers available. However, necessity can often breed desperation and a few more of these quarterbacks may look attractive to teams like the Arizona Cardinals, Jacksonville Jaguars, Oakland Raiders, etc.
The danger of getting the wrong quarterback (either a "bust" or a poor fit) is clear. Once the two-to-three years pass of giving him every possible avenue of success—drafting protection, weapons, modifying the offense and so on—the franchise is a mess and the general manager and head coach are looking for new jobs.
The dangers of never taking a chance on a passer are less severe and often overlooked. The last team to win a Super Bowl without a top-caliber quarterback was the Tampa Bay Buccaneers in 2003. It's a different NFL in this decade and the chances of that happening again are pretty slim.
Before we get to the rankings, one note: These are not the order in which these quarterbacks are graded on my board. While some may consider "power ranking" in different ways, I think of it as which quarterback has the most momentum as of right now (i.e. which quarterback is having the best couple of weeks). That momentum may affect their eventual drafting order, but it hardly affects their level of skill.