I think it is clear NO is the better team, even if they haven't played the strongest schedule to date. The Saints are a top 5 offense, whereas the Bills are a bottom 5 offense. The defenses are probably a wash. The Bills, like any NFL team, look great when winning the TO battle by 3 or 4, but that is very unlikely against Brees and the Saints.
Home field at least gives the Bills a shot, but when the Bills have played legit playoff teams (not the Dolphins from last year) at home, they have often been dominated at home. Just look at our recent home games vs the Pats, the Steelers game last year, and the Bengals game in 2015. I am not sure the Saints are as good as those teams, so the game may be closer, but I just don't see the Bills winning without SEVERAL takeaways.