They have a well run organization with John Elway as team president, a veteran coach with John Fox, a nice young defense and offensive line, and they play in a weak division. They also have $40 million of cap room to make additional player acquisitions.
John Fox made great strides in his first year as the head coach in Denver. They won the AFC West last year with an 8-8 mark and were just one win away from an AFC Championship game last year.
Von Miller leads a great young defense that did a fantastic job of keeping Tim Tebow close enough to come back and win games in the fourth quarter this past year. The offense includes a solid running game behind Willis McGahee, a very good offensive line and a nice young wide receiver in Demaryius Thomas.
Another factor that makes the Denver Broncos so appealing is that they have significant cap room to surround Manning with more offensive weapons and talent. With $40 million, Manning's former teammates Reggie Wayne, Dallas Clark, Jeff Saturday and Pierre Garcon are in play.
Also, Vincent Jackson and free-agent running backs like BenJarvus Green-Ellis, Ryan Grant and Matt Forte are available.
Denver's weak division might be their strongest selling point in comparison to Manning's other primary suitors. Miami has to play New England and Tom Brady in the AFC East twice a year. Arizona has to fight with Super Bowl contender San Francisco in the NFC West. Tennessee has to fight Houston in the AFC South.
Playing in the AFC West puts less pressure on Manning in the regular season because all things being equal it will be much easier for him to make the playoffs.
John Fox is a veteran coach who Manning has been said to be very fond of, and John Elway's leadership of the organization is another strong selling point. Manning can easily to relate to Elway's desire to try to win another Super Bowl at the end of his career.
Elway was 37 and 38 when he won his two Super Bowls. Peyton Manning is only 35. We'll see what choice he makes.