It doesn't matter which one sells more, thanks to SteamVR it's going to be VERY easy to port between PSVR, Oculus Rift and HTC Vive. Unless developers get moneyhatted, or are owned by their respective platform holders, the vast majority of VR titles are going to be multiplatform.
And I'm not getting a minimum spec GPU either, I'll be getting either a Pascal or Arctic Islands GPU in the Summer, assuming that they'll be released by then. I've been saving up for this for 18 months, will be 2 years in November when I get my Rift. You should always have a GPU in your gaming PC being more than half the price of the rest of the components. Anything less than that will give you a CPU bottleneck.
Going to be interesting to see what happens on the 29th February when HTC announce the price of the Vive and open pre-orders. Despite the Nerd Rage after Oculus announced the price of the Rift they're now back-ordered until July
If the HTC Vive is $200+ more expensive than the Rift then I reckon demand for the Rift is going to increase even further...the only thing I can see changing that is having Half Life 3 or Portal 3 as an exclusive lol
Consoles are going to be dead for me next generation, I won't even be getting a Nintendo console for the first time in two generations unless it has VR. Apparently once you experience VR going back to a 2D telly or monitor screen is pretty much an empty experience.