I used to feel I want the fov to be upgraded and visuals 1st but now if I could only have one upgrade, a much lighter form factor is most important to me before the other upgrades. I guess it's because I spend longer times in the headset. I'm probably one of the few that would choose that 1st.
I'm beginning to think along the same lines @inovator
Comfort is the number one factor for me, that either means lighter, or if not lighter, then a very well designed halo, similar to the Rift-S.
Halos are a little problematic for stand-alone though if movie viewing is part of your VR mix, in which case, pure lightness and form factor wins.
A very close second for me is lens technology. Screen detail is now pretty good if the FOV isn't pushed too far for a given resolution and it's the lenses that are becoming the limiting factor for clarity over res. including the size of the sweet spot.
Personally I think the Oculus headsets probably have the best sweet spots but they're going to have to improve further to make res increases meaningful... although the prices of performance GPUs need to make a lot more sense first, or foveated rendering delivers the goods for the more accessible cards.
So yeah, for me, comfort and lens technology.
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