To me it's quite simple: If you can't wait to play pCars or Elite Dangerous in VR, then buy one of these now. If you're not bothered about either title...well there's not much point in buying VR as most of the content seems to be short lived "experiences" rather than end to end, full blown games.
For me, I couldn't care less about controllers or room scale; that's taking niche into a whole new niche altogether, because I don't have room, nor do I want to make room. I simply want an amazing seated experience in some kind of cockpit, and either of the 2 HMDs will deliver this.
FOV? SDE? Focus sweetspot? Comfort?
All valid things to consider, but frankly until the dust has settled and the Vive's are out there, we won't know anything for sure, other than....both will be awesome.