I agonised over the choice between these two but in the end went for the Zenwatch mostly because:
Premium design, square face (don't miss anything with the edges), easier surface (the 360 looks like you hit the edge of the surround when swiping maybe?), customisable with watch straps
I like the idea of having a Wear device that you could disguise as an actual watch which the 360 can do, but it was just too chunky a design for me.
The Zen is slimmer, but I don't think you would look at it and think it was a regular watch before seeing a notification pop up.
Ultimately they are designs where most will simply prefer one over the other because of the shape I think.