Updated: Also had a chance to try Oculus Rift CV1.
I've tried the Oculus Rift DK2 and HTC Vive around April last year, and now made the plunge with the latest boxing day discount. My 3 cents on this:
Hardware needed
GTX 1080 is overkill for everything, provided the software is optimised

;-) In truth, you will hit ASW with 1080 in Elite. It depends heavily on the game played. Vive's resolution (which is the same as Rift's) is 2160x1200 (1080x1200 per eye) and I was able to use both DK2 and Vive in E: D with a GTX 670 and i5-3570K stock. Yes, 670, factory overclocked. SteamVR ready tests listed that as "capable".
Room scale VR
Room scale VR is cool, though you would need at least 1.5x2m space free for it, otherwise you're left with seated mode. Having meet the requirements however it is amazing to be able to dodge or hide behind cover in games like Space Pirate Trainer and Raw Data.
Both headsets are now capable of room-scale
, but in Oculus' case it is labelled "experimental" and you would need to buy touch controllers separately for it (+$200) (Touch comes bundled with Oculus now). Tests show that two cams are fine with small playspaces and 180* tracking, but for 360 tracking you would need a third camera (+$79). Also, the sensors being cameras would require them to be connected to USB ports of your computer. This rules out makeshift solutions like a backpack VR ready pc (used to get "wireless" VR), but this is not an issue for most people. Just keep an eye out for your available USB bandwidth.
Vive uses two passive IR laser base stations, which require connecting to the mains socket and placement high above the playspace. When setup properly the tracking is flawless 360*.
IMHO, YMMV: tracking wise, Vive is far better engineered. Also, roomscale is a thing, even in limited space.
Optics
Both headsets have their pros and cons. If you can't stand the so-called screen door effect (compare viewing something on a multimedia projector), Rift has it less prominent. Both lenses have their own artefacts specific to their construction, Oculus has "god rays", Vive has "lens flares". In DK2 darker colours had a tendency to "smear" - once you see it you're unable to unsee it ;-) All these are dismissible (IMHO, YMMV) in the face of the immersion and depth effect. Also, Vive has a larger field of view, however it has a smaller sweet spot - which is a point where things look clear. The more you look into corners the more blurry it gets so you need to kinda "look with your head" instead of your eyes, a bit like with a led ir tracker. Oculus is said to have larger sweet spot area than Vive.
UPDATE: I had an ocassion to briefly try Oculus today, and can confirm
it has better optics it renders better due to software used, IDK about the sweet spot - I didn't notice edge blurriness typical for the vive so I guess its really bigger. But the godrays are really visible. While in Vive you register them as "unwanted light coming from a strange direction", in the rift every light source "smears" during motion. It is a bit distracting but I think you can get accustomed to it.
Controllers
Oculus touch is a marvel of engineering with its capacitive surfaces and the way it forms around your hand. Having said that, the Vive wands feel comfortable and do their job just fine.
Don't believe the snarky comments about split xbox controllers... they are okay, not as good as Oculus' Touch, but not too shabby either. And HTC is working on next gen controllers, the prototypes are promising. IMHO there is more to the headset than the controllers because they can be swapped anytime the manufacturer releases a new one (see:
http://www.theverge.com/2016/10/12/13264950/valve-vive-vr-controllers-new-prototype) . And btw. give us tracked gloves already and be done with it ;-)
UPDATE: I tried Touch, they are lighter and fancier with their capacitive surfaces. But not as "intuitive" as marketing leads us to believe. I tried the small robot with disks tutorial, and frankly had troubles gripping things if I tried to do it "naturally". Yeah I skimmed through the tutorial ;P but if they were sooo intuitive and natural it would all just "click". I find the buttons too light for my taste. The grip buttons are better than Vive, Vive ones are bit clunkier to use - they are fine for ejecting the clip from your gun, but not for finer operations. Also, you need to be careful on how you place the Touch controller on the table, they have a tendency to roll in unexpected direction when not carefully placed

I'd call it a draw here, and they are definitely not "Vive wand killers".
Ergonomics
Oculus wins this one. Vive still feels more like a prototype with its straps and rubbers. However once you adjust the headset right and learn how to exactly place it on your face so things look clear - you're golden. I don't mind the headset weight with Oculus being the lightest, Vive in the middle and PSVR being the heaviest (and surprisingly the most comfortable one). Also Oculus has these springs you use when removing the headset. Overall Rift is more ergonomic with integrated headphones and more polished design.
UPDATE: I like the integrated headphones on oculus. They are surprisingly good. The headset also is more comfortable to put in/take off due to the springs. I did find one flaw however, IPD feels inferior as it is mechanical and doesn't have any sort of display feedback like vive one does. But, assuming you're done with the demoing your headset to people, you set this once and be done with it - so it is only a minor nuisance.
Both headsets have a built in microphone, I didn't have the opportunity to test the Rift one though. Some people say that Vive mic is "punchy", whatever that means. I haven't experienced that as I played Arizona Sunshine in coop with a friend and had chatted via Vive mics during it all the time, and we played for an hour maybe?
Vive has a front-facing camera You can use the cam for finding out things in the room without taking the headset off. Handy.
There are great things in store for the Vive ergonomics currently:
Deluxe audio strap
Trackers which allow you to track any object you put it on. Note that they are not for the end-user directly but expect to see a range of accessories happening.
Wireless add-on for $250
Elite performance
No matter which headset you go with, Elite will look absolutely amazing with the true sense of scale. You can get a
pale taste of this watching these videos:
https://www.youtube.com/watch?v=6_kLXgo4FC8 and
https://www.youtube.com/watch?v=XjnIPHRMKB0 but it's nothing compared to the real thing.
People say that E: D looks better on the Rift
, supposedly due to some messy coding on FDev's part and/or headset display quirks. I don't have a comparison (I might have later this week). Frontier acknowledged that this is a problem with the software: https://forums.frontier.co.uk/showthread.php?t=247986 but so far not heard of a fix from them.. With the arrival of "HMD Image Quality" many would say that the image is A-B comparable to Rift when you set it to 1.25.
UPDATE: Oculus wins this one hands down.
IDK if its only superior optics or some software problems, but Elite is better out of the box with the Rift. The image is more clear, the text is more crisp and when I looked around cockpit there were no blurriness that Vive has when you cross the sweetspot. The only problem are the godrays in stations - every light source "smears". But lack of aliased edges and crisp UI is a very good tradeoff.
UPDATE2: if you follow the advices in this thread:
https://forums.frontier.co.uk/showthread.php/274325-How-to-get-Elite-in-VR-looking-CRYSTAL-CLEAR-D you can get to the Rift's quality level but it requires immense gpu power. My 1070 is struggling with the 1.5 SS in Steam (that was before SteamVR scale change, 1.5 was something around 3.5) and 0.5 SS in game and it has judder, but the image quality matches Rift's. That would imply that this is not an optics problem but somehow a rendering problem.
UPDATE3: Mystery solved. Rift runtime is able to dynamically/programatically change the supersampling resolution, and has an auto mode depending on performance.
I've done some reading in the meantime and found out oculus software can adjust the supersampling dynamically, hence the out of the box better results with E: D. Thus proving my earlier theory that it has nothing to do with better optics, runtime(? or Elite?) is just cranking the supersampling up. (
see here, render target override description). Plus it gets applied on top of SteamVR supersampling settings. Apparently it can be set to auto and runtime does this, as per
this reddit thread.
Why did I buy the Vive
Room scale is amazing, the passive lighthouses have impeccable tracking. I have 3m x 2.2m playspace currently, if I switch to other couch I will have more (some games require 4x3). Touch controllers are better, but that's not something that can't be fixed with new controllers later.
Again YMMV.
UPDATE: If I were buying a headset only for Elite I would go with the Rift. If for VR in general, especially roomscale gaming - Vive, as it has better tracking and news from CES are optimistic: wireless VR, better harness with headphones and a plethora of tracked accessories coming in 2017 via the tracker thingy.
Fly safe, CMDRs.