Elway didn't have the weapons Brady had but he had a 2000 yard rusher, a damn good offensive line, and one of the best TEs of all time and he never went undefeated.
I don't really get why Dan Marino is so revered. He played on a team that let him drop back 40 times a game and pitch the ball around. Some of the records he broke were held by Fran Tarkenton. Was Tarkenton considered the greatest QB of all time before Marino was? No, so why should Marino be the greatest QB of all time. Not only did he only reach the Super Bowl once, he only reached the AFC championship game twice.
I don't think you can just say ____, ______, and _______ could do what Tom Brady did, especially when a couple of these QBs had similar talent and couldn't get it done.
And again, I think Brady is the best because he's won 3 titles with for the most part average-above average supporting cast.