I voted Aru, Majka and Pinot.
Aru is self explanatory, the most talented of the bunch. I would be very surprised if he didn't end up with some GT wins.
Majka probably isn't as talented as Bardet or Pinot, but he has the advantage that he probably won't focus everything on the Tour. I think he could win the Giro or Vuelta at some point.
Pinot is very talented and if we go by talent alone he should be able to win at least one GT in his career. However, he might be too focused on the Tour and eventually end up with a bunch of podiums at best. I give him the benefit of the doubt, though.
As for the others: I really like Bardet and I hope he wins a GT at some point, but I fear that he will be too focused on the Tour and I don't think he'll be strong enough to win one of these. Peraud? No chance. Rodriguez? No chance. Talansky? I don't think he'll ever be good enough in the mountains and the same goes for Van Garderen. Uran? Who knows, he might be able to grab a Giro win ala Hesjedal's 2012 win, but I don't rate him that high.
Where's Betancur though?
Other riders worth mentioning: Yates and Formolo.