1. Sean McDermott
In 2017, the Bills hired Sean McDermott to take over as their head coach and he's gone on to win over 70 games and lead the team to the playoffs in all but one year. Before coming to Buffalo, McDermott was the defensive coordinator of the Carolina Panthers and helped get the Panthers to the Super Bowl in the 2015 season.
While Bills fans are frustrated by the fact that the Bills can't seem to get over the hump in the playoffs, there's no doubt that McDermott is the best coach in the division. Belichick would have held this spot even after a few rough seasons but now that he's gone, the top spot belongs to the longest-tenured coach in the AFC East, which is McDermott.
I'd be remiss if I didn't say that the heat is defiintely on for McDermott. Unlike the other guys on this list, he's been running the show for quite some time and has little to show for it. The Bills have made one AFC Championship Game and tend to make disappointing exits from the postseason every year.
That being said, McDermott has been the best coach the Bills have had in quite some time and if he were to be let go, another team would likely snatch him up. He's the no-brainer answer for best coach in the division because while the Bills haven't made it to a Super Bowl under him, they've won the division four straight years and are grouped in as Super Bowl contenders every year.