From the Lombardi era:
The Starr sneak for the winning TD in the Ice Bowl. It was the culmination of what Lombardi meant to the Packers (The win over the Raiders in Super Bowl II was, in relation to this win, anti-climactic). The entire winning drive, considering the field conditions and personnel, was amazing. It put on display all that Lombardi had instilled in his teams. Lombardi realized his dream of winning three consecutive championships; in 9 years his teams appeared in six championship games, winning five.
This play isn't just a "favorite". It's iconic. For the fans. For the team. For the NFL. For the sport.
ThxJack, you missed an entire era! How about the decades in between the era above and era below? The losing period of the 70s and 80s... Not a happy era for us fans, but an era never-the-less.
IMO, the highlight of this era would be the 1980 famous blocked FG that Chester Marcol caught and ran in for the winning TD against the Bears in OT.
From the Wolf/Holmgren era:
This is perhaps an odd choice but one play that is etched in my memory is the Dorsey Levens' catch in the NFCCG at Lambeau against Carolina. The Panthers had taken a 7-0 lead on an INT return. Levens ran for 35 yards on 3rd and one to set up first and ten at the Panther's 29-yard line. On the next play, Levens ran a route out of the backfield and up the sideline and drew coverage by a CB. Levens out-leaped the CB to grab a perfect pass from Favre - either Levens catches it or it falls incomplete - in the corner of the end zone and barely stays in bounds. If you find a replay of that play, the crowd goes silent as the ball is in the air and then just explodes at the catch. I knew then the Packers were going to their first post-Lombardi Super Bowl.
My most memorable play during this era is unfortunately the opposite of my favorite. But, it's a play that caused me to be a very grumpy person for months. It's a play that we all know as 4th and 28. Sorry to bring that up.
As for a favorite play, it comes in the SB victory. Desmond Howard's TD return was simply electrifying. The Patriots had all the momentum just moments before and the Packer lead was dwindling in the 3rd quarter. But, that 99 yard kick-off return just deflated Drew Bledsoe and his offensive mates. You could see it in their posture on the sidelines.
My 2nd favorite play (or, in this case "series" of plays) were Reggie White's back-to-back sacks of Drew Bledsoe on the Patriot's series immediately following Howards heroics above. It was Reggie's way of saying, "Don' even think 'bout it!" It was then, still in the 3rd quarter, that we all knew this was Reggie's and the Packers day... Of course, Reggie got another sack on their last series late in the game, just to cap it off. Thanks, Reggie, for that great memory! RIP.
From the Thompson/McCarthy era:
The same as the OP. In Super Bowl XLV on third-and-10 with six minutes to go and the Pack nursing a 28-25 lead, Rodgers ducked into the huddle and said, "We're gonna be champions tonight.'' He zipped it about 30 yards in the air - amazingly it was barely touched by an outstretched fingertip of cornerback Ike Taylor. It landed right in Greg Jennings chest, and Green Bay drove to an insurance field goal. Beautiful throw. Quite literally, had it been one inch closer to Taylor, the ball would have been knocked away, and the Packers would have punted from their 25 with plenty of time for the Steelers to drive and build on their momentum.
Another similar play in this game was the TD pass from Rodgers to Jennings where he hung on to the ball despite it being deflected marginally by the "outstretched fingertip" of Troy Polamalu. Another millimeter in the wrong direction and Polamalu blocks that ball entirely. However, I agree- the best play of the game was the strike to Jennings as you describe above. That was critical and came at a time that momentum was shifting to Pittsburgh. Rodgers had gotten sacked and a penalty made it 3rd and long. That was a great play.
However, another of my favorite plays goes to Kevin Greene's statement to Matthews of "Now is the time" comment caught on audio during a commercial break. One play later, Matthews forces a Mendenhall fumble and the rest is history. Note that my vote goes towards Kevin Greene's comment-- not the actual play. That is the stuff of legends.