These are the quarterback options of the NFL's conference championship round in January of 2013.
Brady is, without question, the most experienced. Not only has he been under center for Bill Belichick and the New England Patriots since 2001—courtesy of Mo Lewis—Brady has started in five Super Bowls.
The fascinating perspective among these four signal-callers, though, offers the beginning of one's career in Colin Kaepernick. He is literally Brady's polar opposite regarding experience; however, he came into the starting role for the San Francisco 49ers in eerily similar fashion.
In short, it's quite ironic to see Kaepernick beginning his journey, while Ryan and Flacco are in the middle. Brady, of course, is down the final stretch at age 35.