The Seattle Seahawks, New England Patriots, and Pittsburgh Steelers are all tied with the best odds at 8-1 according to the Westgate in Las Vegas, which makes sense considering the talent that both team have. After those three, the Green Bay Packers, Arizona Cardinals, and Carolina Panthers are tied with 10-1 odds, while the Cincinnati Bengals and Denver Broncos both have 14-1 odds. The Dallas Cowboys have the ninth-best odds at 16-1, and then three teams are tied at 20-1: the Minnesota Vikings, Indianapolis Colts, and Kansas City Chiefs.
Looking at the top 12 on the list, it stands out that ten of the teams made the playoffs in the 2015 season while the other two, the Cowboys and the Colts, dealt with the loss of their star quarterback for over half of the season (the Cowboys' Tony Romo missed twelve games, while the Colts' Andrew Luck missed nine games).
For the Colts, it's clear that the reason they are included with other playoff teams is simply Andrew Luck. His return to the field in 2016 should help stabilize the team after a rough 2015 campaign, and with Luck healthy the Colts will still be expected to make the playoffs. That's why they have 20-1 odds and are tied with two other teams that made the playoffs last year, but the reason they're not higher is because we saw how much work the team still has to do in order to be a Super Bowl team. With Luck back, the Colts look to be a playoff team once again, but unless the team improves other areas (such as pass rush and offensive line), they likely won't be a Super Bowl team. The good news is that the Colts still have an entire offseason ahead of them in which they can improve, and if they do that, it wouldn't be a surprise to see their Super Bowl 51 odds improve either.
Here's the full list of the odds, according to the Westgate in Las Vegas (h/t to Niners Nation):