I think almost without question that Rodgers throws the best "Hail Mary" ball in the history of football. That one vs. Detroit was the best in terms of just the sheer perfection of height, distance, and accuracy. While there certainly was an element of luck in the fact that lumbering Richard Rodgers ended up in the perfect spot, what wasn't luck was that there are probably less than 5 guys in the history of the planet that could have put the perfect height and distance on that throw.
For Favre, sadly one of his best throws that I can remember was one that was dropped. Final drive of Super Bowl XXXII vs. the Broncos, we all remember Favre's final 2 throws that didn't look so hot. On 3rd down he missed Robert Brooks by a yard, and then on 4th down, the Pack is in panic mode and Favre throws short to Chmura ending the Packers hopes that night.
However, that 2nd down pass on that drive, it was completely overlooked at the time because the announcers actually said it was knocked down by the Broncos. Truth is, it wasn't touched by a Bronco. As a matter of fact, the pass was so perfect, I think it shocked Antonio Freeman so much that he dropped it. There were 2 Broncos that were closing on that ball that was hummed in there that you thought for sure that one of them could knock it down, and to the naked eye, that's what it looked like happened. But the real honest truth is, that pass was perfect, just hard enough that it whipped by both Broncos defenders before they could reach it. It hit Antonio Freeman in the perfect spot for him to catch it in stride and unfortunately it bounced right off of him. If he catches that ball, the Packers either score on that play or Freeman takes it right to the red zone and we never see those unfortunate 3rd and 4th down throws.
Favre had a poor 4th Quarter in that Super Bowl, but that 1 pass was just so good I will never forget it, and I always wonder what could have happened had Freeman caught that one.