If Quintana is on form, he's the most likely winner. We really have no idea of his form, after winning the Tour de San Luis he's not raced much. But he is a top climber, decent TT, strong team, suited to the mountainous route.
I think Rodriguez is a punchy climber with a strong finish, not sure he is up there with the best on long climbs. Something like Quintana, he won a stage race early in the season, and hasn't produced much since.
Evans started the year with good form at the Tour Down Under, and seems to be getting better with the Giro del Trentino win. I don't think he can keep up with the very best on the long climbs, but his steady experience could help him avoid problems and capitalize on others' mistakes.
Basso doesn't seem in the same class as the others. Hesjedal hasn't done much in the past year. Uran lacks team support.
Those are my three front-runners. I'm picking Quintana and gambling that he's been training hard in the Colombian mountains and not staying up too late changing diapers.