I think if you are under 35 its very difficult to judge all time great QBs. You just havent seen enough football.
Even at 54 I have to admit that i didnt see Johnny U in his prime...or Baugh , or Otto Graham.
Brady is certainly an excellent QB due to incredible cool, the ability to slow the game down, a good not great--but accurate arm.
He is certainly top 10 from the last 40 years.---I do not,however,see him as the type of QB with the skill to carry
mediocre teams on his shoulders like Marino and Elway did.
I will give Brady credit as being the closest thing to Joe Montana in the 'keeping your cool' dept on the field.