Halo, I am very curious where they take the series. The franchise is in a little trouble, the online population tanked and 343 needs to recover. This is Microsoft's biggest IP so they will be giving it everything they have. If it sinks, so does the Xbox One.
Titanfall, I feel like this will be the next big exclusive IP. Shooter popularity has reached a fever pitch, and having the player in the body of a gigantic robot will please many. They have put a lot of effort into ensuring there is capability for a competitive scene, with pro gamers giving feedback on game mechanics and balance. I don't feel like there is any title that will compare. Maybe I'm overly hyping it though.
I agree about Halo, although I personally don't think the series needs to be "saved." I don't think the multiplayer was quite up to snuff in Halo 4 but it wasn't bad by any means. I used to be awesome at Halo 2 multiplayer, and pretty decent at Halo 3 (I didn't play much), but I absolutely sucked at Halo 4 multiplayer. I enjoyed Halo 4's campaign, though, and I have high hopes for the future.
I cant say there is one game I am looking forward to, but several and they are Titanfall, Halo 5, and Destiny. These three are the games I want the most for games coming out in 2014. Other games I also am interesting in are Thief, The Witcher 3, Watchdogs ( bummer that game got pushed back), The crew, Quatum break, and The Division.