Definitely on New England. I'm not so certain about the Chiefs. Their wins so far:
Jags - Minshew's first game coming in for an injured Foles
Raiders - Awful
Ravens - 5 point win. Ravens probably an 8-8 team.
Lions - Scored in the last 23 seconds to win the game. Lions look decent this year but we'll see how that plays out.
They still play Chargers (x2), Texans, Packers, Vikings, @Bears, @NE
Certainly not a cakewalk left for them. Their defense is awful, particularly the run D. The OL isn't very good either. They can put up a lot of points, but they face a number of top 10 defenses the rest of the year.
That being said, looking at the current conference standings it'd appear that the Texans will have the best shot of taking it from them. I can't see anyway the Bills manage to keep up their current pace.