If you are in the EU, what VR hardware would you point to which would be well positioned in the price / quality equation ?
And the other day I discovered that the knuckles controller is compatible with old Valve headsets, any chance it could be compatible with other brands ?
My recommendation is an Oculus Rift S for an affordable (in comparison to Index) solid solution. Some people don't like them because they fund/develop exclusive games likening them to Epic (even though generally it doesn't seem like they just pay pre-existing games to get on their store exclusively but actually fund their development, there's been no prominent game announced for VR only to be revealed as an Oculus timed exclusive later on although some older Oculus games did eventually make their way to other platforms) but the hardware works with SteamVR as well.
I have an original Oculus Rift myself, the one with the camera trackers needed all over the room, and it's been wonderful. I was reading reviews of WMR sets, Vive and Rift for hours daily before deciding back then and I feel I made a good choice. If I made that choice now, to me it seems like it's an even easier choice. If you have the money to burn on gaming you get an Index, if you want something affordable you get a Rift S. WMR appears abandoned from Microsoft for now and Vive just isn't worth the asking price unless you can get a cheaper used unit thinking you can then upgrade to the compatible with it Index controllers (which cost almost as much as the full Rift S kit on their own). But not the Vive Cosmos which appears to be a more expensive yet inferior in many ways Rift S.
With that said, you need to check if your
IPD is among the common average because Rift S ditched the hardware switch and only offers software correction so the range of compatibility is slightly smaller. The original Rift has a hardware switch, the Index has a hardware switch and from WMR sets only the Odyssey and Odyssey + have a hardware switch (but I'm not entirely sure of the ranges on all of them, maybe for some it's not much different to the S). Still, from all reports and reviews (and just looking at the thing with all its cameras) Rift S offers better tracking than any WMR set (they all run off the same 2 camera standard even if they differentiate in build quality and screen quality), especially after last year's substantial tracking update. I wouldn't dwell too much on the most egregious angry posts regarding IPD, you'll find similar for every set out there, some people claim the sweet spot on the Index or Odyssey sets for the lenses is too small and hard to get to without making it uncomfortable to wear and things like that for example but I doubt Index has such a deficiency.
As with every product it would be great if you can at least try it before you buy, preferably with a friend who knows how to set it up for you so that you know you get the right experience (the first time I used my Rift it was quite uncomfortable and I couldn't get the IPD right until I fiddled around with the straps and everything to properly set it on my head and face without too much pressure) and try the right introductory software.
I also like the Oculus software itself, it's simple, to the point and functional, especially after they gave us the option to disable the actual Home area and simply get a blank space with the Oculus dashboard and stuff in it. Plus the first set up and tutorial experiences like First Contact were the best intros to VR I've seen.
Plus, other than Valve's new Half-Life: Alyx game, Oculus is the only one to have funded high production value games that help push VR and its marketability from day 1. Though most all of them are playable with any VR set (the hand tracked ones ideally with an Index as it matches the controller layout better) thanks to the Revive software (new games might have issues, like Stormland, but it's probably going to be worked out soon enough).
Lastly, if you also want some stand alone VR games without being tethered to a PC then the Oculus Quest might be a good choice (it has plenty good ports of lower end games like Beat Saber, Pistol Whip, Apex Construct, SUPERHOT VR and others that don't really lack much from the PC counterparts but other ports aren't as good or ever exist at all as it's still running off a mobile chipset) but only after people test and approve the newly-in-beta Quest Link service which allows it to tether to a PC and, theoretically, function almost like a Rift S for PC VR games. The software only just released, the official 5m+ cable has yet to release and the currently recommended 3rd party cable is only 3m so it's not a known factor until people test with other longer cables. The Oculus Quest also uses a hardware IPD adjustment just like the original Oculus Rift, unlike the S, which may be a contributing factor for your decision.
I should note the original Rift has a 90hz display, the S 80hz and the Quest 72hz. Index goes from 90 to 144 (good luck running high end VR games at 144fps).
Of course we should wait for confirmation on exactly how Half-Life VR plays because for all we know it might only work with Index. I doubt it, the only reason that was the case with Aperture Hand Lab is because it was exactly that, an Index controller tech demo. They wouldn't ban ~50% of the VR market share products (that is Oculus going by Steam hardware surveys, then Vive at ~35% then pitiful amounts of the rest) from playing their flagship VR title but you never know. The current Index poster child, Boneworks, appears to work just fine on Oculus controllers too so hopefully, most likely even, that's the case for Half-Life VR too. They both probably work with the limited Vive wands, even if that makes the controls clunkier as they don't have enough/good enough inputs.
Edit: and no, no chance of Index controllers being compatible with anything that doesn't use Valve tracking. So, Index, Vive, Pimax, ie, nothing budget concious.