As I will be for the next few years, I'm all-in emotionally on Mickelson. Love him or hate him, seeing him complete the Grand Slam would be good for golf, and AMAZING television.
Realistically, I expect one of the big boys to win this one. Brooks, DJ, Rory. Pebble always has teeth in an Open setup, but there's nothing they can do to make it any longer, so bomb-and-gouge still works.
If you want to bet outside the favorites, Finau has put up some really solid performances lately, and Fleetwood seems to be where Molinari was two years ago - ready and waiting to explode. If Spieth can find a fairway, he'll be right in it. Tiger could hit stinger 2i off every tee every day and probably shoot -6 for the week regardless of conditions. If the weather is shit, that might be good enough.
Force me to make a pick, and I take DJ. But I don't like how that feels, so let's go with Xander.