OK here is how I see it. I am going off of postseason and SB performance.
The reason I do that is because to separate the great from the best you have to see how they play when it really matters and for the team to make it to the playoffs the whole team has to be good. I list TDs vs INT in Playoffs because INTs in the playoffs are the most telling stat in whether or not the team wins or losses.
Montana 4 SBs wins 0 lost beat Marino postseason record 16 wins 7 lost, 45 TD 21 INT
Drew Brees 1 SB win 0 lost beat Manning postseason record 4 -2, 13 TD 2 INT
Tom Brady- 3 SBs wins 1 lost Wins postseason record 14 - 4 28 TD 15 INT
Peyton Manning- 1 SB win 1 lost postseason record 9-9 28 TD 19 INT
Marino 0 SB wins 1 lost to Montana
So far Montana is the best. Sorry.