I would expect most people think Dallas is the best team in the NFC. It's to be expected since Dallas had home field advantage throughout the playoffs last season, and they only helped themselves this offseason by adding two 1st round picks (CB Mike Jenkins and RB Felix Jones) and CB Adam Jones to their roster.
One thing to watch this season is injuries in Dallas which are starting to become a problem. The writers of the Pro Football Prospectus had projected Dallas in 2007, and again in 2008, to finish behind the Packers. The biggest reason why Dallas defied the stat head prediction is injuries. Early in 2007, Dallas lost WR Terry Glenn and DT Jason Ferguson to season ending injuries. After that they lost no one. Nearly their entire roster was injury free. That wasn't great coaching or training, that was a fluke. Dallas might defy the odds again in 2008, but eventually the statistical exceptions fall back to earth.
From Pro Football Prospectus 2008:
"What was more surprising was the ability of the Cowboys to avoid the injury bug, a bite they've eluded since 2003. Over the past five years, the Cowboys have been the healthiest team in football by a significant margin. The second place team, Houston, is closer to 12th than it is to Dallas."