Unitas. Staubach. Montana (even though I hate the 49er's). Bradshaw. Even QB's like Plunkett and Brady (and God, oh God do I hate the Pat's) rate above Manning.
Why? Because they led their teams to Super Bowls (Note I said "led". That way Dilfer doesn't count).
Manning is one of the best to ever play the position. But he wont be one of the greatest until he leads them to a Super Bowl. And it's not his fault his defense will keep that from happening. It happened to his dad. It happened to Marino. And to players like Ted Williams, Sir Charles, Karl Malone, Tarkenton, and many others. Sucks to be them.
What do players like Dr. J, Elway, Yzerman and Hakkem all have in common? They made sure they will always be considered some of the greatest at their sports becuase they won the big one. As it has always been, so it will always be.