Lately there has been a debate on what HMD has the widest field of view. the debate started on reddit and has been discussed on vrtalk.com.
So far the comparisons contradict one another. While some users simply overlap the view of a single lens from each HMD others simply state that this is completely useless if distance from the eye to the lens is not taken into account, distance that may vary between Rift and Vive.
Another user who tested both HMDs, said that while he does not dismisses the rumors that Vive might have a bigger FOV on the overlap test, he did not notice any difference between the two. However will have to wait a little more to see rigorous tests and how much FOV has an impact on the overall image quality of the HMD. In the end, the entire experience means more than FOV.
In our experience we have learned one thing: never lean too much on paper specs. Lets wait for both of these and see if there will be a clear winner.