Which VR headset to choose

"I don't own a PC VR headset for the reasons it's much more expensive than a PC monitor and I don't want to spend so much money for games that look like just technology demonstrations." - E3NBF

There's so many flaws here I don't know where to begin.  But to start with, Half-Life: Alyx and Lone Echo are not games you can dismiss as 'technology demonstrations,' they're great games.  Not to mention Rise of the Tomb Raider, Skyrim VR, VTOL VR, Until You Fall, The Walking Dead: Saints & Sinners, Contractors, Raw Data, The Room VR, Beat Saber, Pavlov VR, Arizona Sunshine, and Elite Dangerous.  Or for that matter, the huge number of other good VR exclusives on the Oculus store.

Now, that said, in normal times, you would probably be able to get cheap WMR headsets on the used market in the $200 price range you mentioned in your original post, but from what I've heard there has been a tremendous surge in demand for VR headsets recently following the release of Half-Life: Alyx (a VR exclusive game).  So your price demands are extremely unrealistic given the circumstances.

Here are a range of PC VR headsets I suggest you consider, and their prices:

Oculus Rift S....   Decent budget headset for $400 (huge library of VR exclusive games)

HP Reverb G2....  Mid range VR headset for $600 (with pre-order discount)

Valve Index.... Top tier VR headset for $1000

That discussion of price brings me to your other comment that I need to respond to.  You say of VR:  "it's more expensive than a PC monitor." Actually, the prices for VR headsets I listed above ($400, $600, or $1000) are typical price points for good quality computer monitors or HDTVs.  So no.. it isn't really more expensive to get VR than it is to get a computer monitor.

That said, the Oculus Rift S is probably best suited to your needs because of its relatively low price ($400) and large library of VR exclusive Oculus games.  I personally believe the HP Reverb G2 is most likely a better value since it's only $200 more and has more than double the resolution of the Rift S, but if you want to minimize the price and increase the number of good quality VR games you can play, the Oculus Rift S is your best bet.