On paper, the US
But when the games start, Canada.
Given that 5 of the Dmen from Canada are returning players, who all played very well at last year's tournament, we know that Canada's D can play. However, this time around, the Tournament is on the International sized ice, so that is going to be interesting to see who can adapt. I hear Canada is holding camp in Calgary, so I hope they are going to be practicing on the big ice surface to get used to the difference.
I recognize Johnson, Johnson, and Lee, but not the other 4 guys for the US. Lee was a disappointment at last year's tournament, so he'll need to turn it around.
Based soley on talent, J&J are the 2 best. But, Canada overall has the better depth, as there is very little dropoff from #1 to #7. And in a short tournament like this, where you have back to back games, not having to rely on 2 guys to each play close to 30 minutes a game will keep the D fresher for Canada. If you have 3 excellent pairings, then at most, the top ice time for the top pair should be about 22/23 minutes.
Bourdon/Letang will pair up again and should be expected to bring some offense
Parent/Staal will pair up again to shut down the top line
That leaves Russell to pair with one of the new D men.