The Packers have a more loyal fan base.  

Packers have a waiting list.  Last I heard the expected wait is about 20 years.  

Vikings have been selling out lately, but If you buy them early enough some single game tickets are still available.  

Minnesota fans are pretty fickle. When the Vikings are winning, the fans love 'em. When they're losing, we call them the worst team ever. I do it, too. Even when they're winning, I cringe and wait for them to throw it away. I can't be comfortable unless they're ahead by 28 points. Packer fans I know are all die-hards. They don't care whether their team is winning every game or if they're in a slump. They just love their Packers. It's hard to blame them. It's a good team, overall. I'm just a homer. It doesn't make sense to support a team outside my state.

Having been to both stadiums through the years Packer fans, easily. But I say that not because of any tangible on the field, but rather because in Green Bay the Packers are literally the only game in town. In Minneapolis you have 6 professional franchises to choose from, 2 of them whose season runs concurrent with the Vikings. Beyond that you have about a million other ways to spend your "entertainment" dollar, it Hennepin Theatre offerings, the Guthrie, Walker, Ordway, etc.

When you are the only game in town it is a lot easier to attract a rabid fanbase that will stick with you in good seasons and lousy ones (when they have them)

The Packers most definitely have the more loyal fan base. However, after having lived in Dallas, I would argue Cowboys fans and Saints fans are also ridiculously loyal to the point of violence. So many fights! Regardless, I love professional football and will root for the Vikings, but I still prefer the collegiate level.

 
LJ, xx

Fans are the same everywhere. When the teams win they are loyal when they lose people jump off the bandwagon. Look at NFL ticket exchange and you can buy tickets for any Packers game just like every place else. I have been to Lambeau when the Packers were losing and the "fans" booed them off the field. Remember that Monday Night game when they were getting pounded by the Titians and there was a shot from the blimp in the third quarter and they were streaming out of that dump like rats leaving a sinking ship.