I'm a bit unsure on how the race will play out. Because there are so many sprinters none of them might win multiple stages, which means consistency and placings is most important.
If say the winners went like this - Greipel, Cavendish, Goss, Chicchi, Rojas, Farrar. It would come down to who finished 2nd/3rd the most, who won the intermediates, or who (if any) got time on the harder stages. This also opens the door to an adventurous non-sprinter (say Ballan) to win a stage with a 5s gap - that would almost be enough to take the GC.
The only rider with the potential to dominate the four flat sprint stages is Cavendish... its too tough for Greipel or Farrar to win more than 1-2. Davis is a bit of an uncertainty for me, his form is definitely better than last year, but if he was in peak shape he would have been in the leading group last week.
I will probably back Cavendish, Goss and Rojas for the overall plus a few non-sprinters as cover.