1. 12 Years a Slave
In the battle between 12 Years a Slave and Gravity, I still give the slight edge to 12 Years a Slave. The subject matter, while maybe a bit difficult to stomach for some when presented in such a stark and unfettered manner, is right up the Academy's alley, and I'm sure there are many an Academy member who are only too eager to declare possibly the first serious cinematic endeavor to tackle the issue of Southern Slavery, a Best Picture winner. Also, the film is much more likely to appeal to the Academy's Actors branch given how technologically dependent Gravity is, which is a definite advantage for Steve McQueen's 12 Years a Slave.
Nomination Chances: 99%
2. Gravity
Gravity has become a cultural sensation. With three consecutive weeks atop the box office, approaching nearly $200 million in U.S. box office, for most of the public, Gravity is certainly going to be one of the most memorable experiences of the year in film for 2013 (definitely more so than 12 Years a Slave, which sadly far too few will see). For some in Hollywood, every extra million dollars Gravity makes is another convincing argument in its favor, although as we saw in 2009 with Avatar, all the money in the world doesn't necessarily buy you a Best Picture Oscar, especially if you're a science fiction film.
Nomination Chances: 98%