it's debatable. i personally would take elway or marino over peyton though. i'm not really a big believer in using the crappy team argument to defend a player but Marino for most of the 80's and 90's prior to Jimmy Johnson coaching there had some bad teams where he didn't have much help and he still put up numbers. When Jimmy took over and started building the defense and putting a team around him it was clear his beat days are numbered.
for elway, he put up some great numbers both with his arm and legs throughout his career and played well in the playoffs as well. super bowls aside, he stepped up in the clutch when it mattered.
not saying it as if it's a fact. i'm sure you can make an argument for peyton being better then those guys but i got my reasons why i'd take elway or marino over him.