That's a tough question, a few weeks ago the Saints, Rams, and Chiefs were red hot, and those were the teams to beat. Now a few weeks later, all those teams have had poor performances.
The Rams had a poor performance in Detroit a couple weeks ago, despite the win, and then they looked so sluggish last Sunday night.
The Saints only scored 10 points in a loss to Dallas, and looked slow in Tampa most of the game.
The Kansas City Chiefs lost Kareem Hunt, and barely outlasted Baltimore.
The Patriots basically won in Miami, it would take a miracle to get a touchdown with 7 seconds left on your own 31 and no timeouts. The luckiest phenomenon in the NFL happened which resulted in a loss for New England, but only on paper.
The Chargers could be 11-2 but instead stand 10-3 and have been very consistent on both sides of the football this season. Only problem they're facing i n the near future is choking. You just can't trust the Chargers. Period.
The Bears defense is playing very good, as well as Trubisky and the offense. They're near unstoppable at home but on the road is a different story.
The Dallas Cowboys are similar to Chicago this season, a great defense and Dak and Zeke on offense, but they are inconsistent because of how many unacceptable road losses. They won't get far until they turn that around.
The Seahawks have won 4 in a row recently and are now 8-5. You can never count this team out.
The Pittsburgh Steelers are the last contender currently. Stagnant and sluggish team. No Bell does not help matters. They hung in there last year with so many close comeback wins against below average teams, but it's not working this year. Ben is old and beat up, he can't do it anymore. No defense for years now. This team has seen better days.
And lastly, the Texans just aren't that good enough.
I know this doesn't answer your question, but I gave you a list of teams who are contenders for "the best team in the NFL overall". In my honest opinion, I'd pick the Patriots. They basically lost 3 games this year thus far, and usually average 3-4 losses a year in the Brady-Belichick era. They get really hot come playoff time, and I say Brady gets his 6th.