The 2016 World Championship Candidates Tournament starts in a few days, and I must say the field is pretty open. There are a few players who definitely can win it, a few players who might win it, and the rest who can affect the outcome.
In the 'can win it' category I would place Fabiano Caruana, Viswanathan Anand, and Lev Aronian. In the 'might win it' group, Nakamura and Topalov. As for the other 3 players, Svidler, Giri and Karjakin I would be surprised if they did finish on top, but it is still a possibility.
If I had to settle on one player, I think it will be Caruana. While not recently dominating the chess scene in the same way he did at St Louis 2014 I think he is in the best place career wise to qualify for the World Championship match. He is just at the right point regarding youth plus experience to have both the skill and energy to go all the way (at least until he reaches Carlsen).
The tournament starts on Friday and you can see all the action at the tournament website (and possibly no where else!)