Peyton is really that great. Just like Kelly and Marino, who were both shoe-ins for the hall of fame.
But he's not a winner like Brady. At the end of the day, the only thing that ever matters in any sport (football included) is winning your last game of the season. Brady did that more than Manning. So he's greater.
You get paid to win. Not pass for 400+TDs, even if it's a nice stat.
I wonder who's the more marketable draw for a team/league though. Is Peyton a better money maker for owners/league, or is Brady a better pay-day? Factor in merchandising, ticket sales, endorsement deals, concession stands, etc...
In pro sports, making the owner money (even if you don't win the last game) can't be ignored.