Before he was "that idiot on TV every Sunday," Terry Bradshaw was "that idiot who won a bunch of Super Bowls with the Steelers." His numbers weren't all that great, and some might even say he was a bit overrated, but Bradshaw was fortunate enough to be on some Steelers teams that were absolutely stacked, and that got him some serious hardware. He and Joe Montana are the only players ever to start at QB in 4 Super Bowls and win them all. He struggled with interceptions early in his career, but developed into a damn good QB and field leader, and went on to be one of the most successful quarterbacks of all time.
Yes, he's still young. Yes, he is only in his 5th full season as a starting QB in the NFL. But anyone who is paying attention can tell you that Rodgers' first four seasons are as good as any 4 seasons that any QB has ever had, and his 5th one is shaping up to be more of the same. Rodgers' career is still very young, but he already has a Super Bowl win (and a Super Bowl MVP) under his belt along with a regular season MVP, and it wouldn't be surprising at all if he picked up a few more along the way. He's the all-time leader in passer rating, and leads all active QBs in yards per pass attempt, completion percentage, passing TD percentage, and interception percentage. Since he took over the Packers in 2008, there has been no one better.
Many people know Jim Kelly as the hard-luck loser of 4 consecutive Super Bowls with the Buffalo Bills. While that is certainly true, it's a bit unfair for a guy who was a remarkably good passer for a solid decade in the NFL. It might be a bit depressing that he lost 4 straight Super Bowls, but there are hundreds of other quarterbacks who would have loved the chance to play in a single Super Bowl, never mind 4 in a row. Kelly was a huge reason the Bills continued to dominate the AFC, and was an elite passer for a decade in the NFL. If anything, he's a bit underrated now, thanks to the ignominious honor of being the most prolific Super Bowl loser in NFL history.
He's certainly the greatest ever to wear the number 12, but it's moving beyond that at this point. Tom Brady is making a hell of a case as the greatest quarterback ever to play the game. In 2010, he was the first person to be unanimously voted the NFL MVP by the AP voters. In all fairness, it should have been his 2nd unanimous MVP, but one voter inexplicably voted for Brett Favre in 2007, when Brady turned in arguably the greatest season ever for a QB. Brady's career TD-INT ratio of 329-119 is incomparable among QBs with over 5 years experience, and he has developed from a 6th round pick into the greatest in the game. Without a doubt, Tom Brady is not only the greatest quarterback ever to wear the number 12, he's the greatest athlete ever to wear it.
In fact, 12-12-12 should hereafter be called "Tom Brady Day." Don't ever let anyone tell you otherwise.
Feel free to pick apart my list in the comments section below, if you disagree with some of the rankings or think I omitted someone. All feedback is encouraged.