Hey Bruce, it was a number of things but before I answer, I need to say everyone should do what they think is best for them. I'm not trying to sway anyone. Just answering why.
This generation of headsets, while an improvement over DK2, isn't a revolutionary improvement - except in the case of the Vive until Touch comes available which supposedly isn't until Q3 or maybe Q4. The resolution and SDE is better than DK2 in both but apparently not by a huge amount. Tracking is supposed to be better in the Rift but is full-room in the Vive and there are videos of twirling the Vive controllers on their safety straps with full tracking. Plus you get controllers now rather than waiting.
And I think that wait is significant for multiple reasons. The reviews I've seen weigh heavily in favor of the experience you get in the Vive with them. I know they aren't so important for flying or driving. I use a wheel and HOTAS for that. But for other things where I can involve family, they will be key. I have nieces and nephews, grand nieces and nephews, who will go nuts over Tiltbrush, Space Pirate Trainer, etc. That moves me from the nerdy uncle doing his VR stuff to the cool uncle that lets you paint and fight the evil empire, etc.
But the other reasons that wait is significant is that from everything I've read, this round of HMDs is looking to go clearly to the Vive and the reason is the controllers. I think support in the other stuff I like to do is inevitable because instead of being an also ran, it may just be the leader out the gate. I know that's speculation but there are a lot of people canceling the Rift and ordering Vive. No way to know the actual numbers, but there are lots of posts being made to that effect on all the boards. The general public is not so enthusiastic about sitting experiences without tracked controllers with the Vive to compare with with tracked controllers and the experiences that opens up. We in the flight and driving sim worlds are still a niche and no matter how good the Rift may be for that, even in the general flight sim world, acceptance remains low since it is something that has to be experienced to really get. I've posted a number of times on the flight sim boards about how VR adds so much to the experience and have been basically heckled about half the time.
And the last reason that I have that the wait for Touch is significant is that I really don't expect this generation of HMD to be that long-lived. Again, my speculation. But Oculus seems to have been caught pants down this generation and the response in the general reviews has been strongly to the Vive because of the controllers. When Oculus comes out with Touch it will really only be comparable to the Vive and not be the leap ahead that is required to win back the people going Vive. Likewise, HTC and Valve have the lead now which will go away to some extent when Oculus can deliver the Touch. Both of them have huge incentives to come out with gen 2 soon to either maintain a lead or regain a lead. Add to that that we already have two companies with eye tracking tech and support is going into drivers for foveated rendering, Pascal (and the AMD equivalent) is on the near horizon, and the technology will soon be in place to allow the jump in resolution that is always mentioned as a drawback to both HMDs in reviews now.
I've seen discussions of lens flare and such but they both will suffer from that due to the Fresnel lenses. Even if one has more flare than the other, I think from everything I've heard it can't be too big of a difference. There may be some ergonomic differences, but the DK2 is still the worst of CV, Vive, and DK2 by far and I've been quite fine flying for extended periods. Either Rift or Vive have to be better and again, small differences don't seem like a reason to forego the tracked controllers and experiences now.
So while going Vive is a bit of a gamble for flying and driving, I still have the DK2 and can run FlyInside/FSX/P3D and DCS just fine. I can't drive anyway since I really don't care for ProjectCars. Unfortunately Assetto Corsa quit updating the runtime. It will take them a while to get support for either Vive or Rift in place and their head said they are working hard on their PSVR release instead. I think they will come around, but don't know. I really, really like AC. It's almost as fun as flying for me and that means I really love it.
I just didn't see keeping the Rift and spending $600 for something only a bit better than what I have now. I'm sure FlyInside is really great with the CV, but so far Dan said Vive looks promising. I know that's not a guarantee but again, I still have the DK2. I had to make a decision because I'm pretty sure I was in first wave and Oculus had been saying that they would be arriving last Monday. I know I could have scalped it but there are reasons why I didn't want to do that. I could easily have bought both but it's just not necessary for me after thinking about it a lot.
Sorry for the wall of text, but you asked.
My reasons only and everyone should make their own decisions.