Henry is a big favorite right now, and it would be surprising for him to lose.
Two things to note:
Alabama is an ok team in a pretty poor year. I don't have any big problem with their top 4 status, but I recognize this isn't one of their better teams of late. They do one thing really well, and that is their truly elite level rush defense. They can simply take you out of any idea you may have had of rushing the ball. That covers up a lot of holes, but most significantly, it means they are usually ahead in games. Alabama has had the opportunity to feature Henry as much as they want in meaningful action.
Secondly, and in particular respect to teams like Clemson and Stanford, Alabama is on prime television a lot. Good time slots, good networks, and many eye balls. Stanford had 7 games start later than 7 pm pacific time! Tough to win voters if they're asleep.