Interesting question! When you've got this kind of parity in a division, it often comes down to intangibles like coaching. Norv Turner can win games if he has good weapons, and he does....but in close ones, his record is not good (because he's not a good HC).
Denver is a train wreck right now. They ended the season that way and it's only gotten worse since then (unless anyone is stoked about those weird FA signings).
I actually believe that KC could win this division. They have weapons on offense, a smart new set of coaches - they do have some issues on DEF, but none of these offenses are scary. Rivers did have a good year but it's a bit premature to call him HOF material. He's had some wildly inconsistent years, as well. And if something happens to LT, as much as I like Sproles, there's no proof he can be an everydown back in the NFL.