I think Dallas wins going away.
The Saints haven’r yet seen a defense like the Cowboys defense
The Saints played Baltimore @ Baltimore in week 5, outdoors in the cold. Baltimore is currently 1st in yardage allowed, 1st in scoring allowed, 1st in passer rating allowed, 2nd in passing yards allowed, 3rd in rushing yards allowed and 5th in defensive DVOA. And the week before playing the Saints they had 11 sacks. Against the Saints they had 1.
Cowboys are well below Baltimore in all those categories and are currently 13th in DVOA (Saints are 14th, FWIW)
They also played Minnesota in Minnesota, a very difficult place to play. I don't have all the Vikings defensive stats on hand but I don't think anybody would argue that they don't have a very good defense (currently 6th in DVOA)