Some say Amour. At this point, I don't think it is a contender. Just because Amour got a Best Director nomination DOES NOT mean it gets an extra boost. That's like saying 'Beasts' is ahead of 'Argo' just because of a directing nomination. Fortunately the Adapted race is locked up for Chris Terrio.
So it's a two-horse race between Zero Dark Thirty and Django Unchained. The bad thing is that both films have their fair share of controversy. 'Zero Dark' won the WGA, 'Django' won the BAFTA, and is the expression of voter overlap. I say 'Zero Dark' has the advantage due to the fact it's ahead of Django in the Best Picture race.
If the Globes expressed voter overlap, I would say 'Django' would be leading, but I also have to give 'Zero Dark' a boost due to impulsive voting with the WGA.
Mark Boal, Zero Dark Thirty