Think you have to add Half-Life Alyx here too now, probly at the top of the list.
Aside from the one's already listed above I'd say the following should be considered top tier:
1) Pavlov-The King of FPS on VR
2) Valve's The Lab-It's mostly a minigame collection but extremely high quality in each one.
3) Blade & Sorcery-VR's own top tier sandbox
4) Tetris Effect-Only downside is you have to download the Epic Store...then use SteamVR to play this. It's worth it though
I'd also give a shoutout to a lot of "Non Games" for VR that should be consdiered "Must Haves".
1) Google Earth: Travel the World (start with New York!). You can fly like superman, then dive to street view and see the actual sites. Both fun and useful, if you're going to travel you can see your destination ahead of time.
2) Space Engine: The "Mind Blown" app of VR. Start at earth and start travelling and realize...we are so very small. The actual size of the known universe compared to our own corner is just impossible to realize till you see it.
3) Virtual Desktop: Want to play a youtube video on imax, or a movie from Amazon? This is how. It turns your desktop into a viewable window of any size, and has special rooms like turning into a theatre or making a supremely giant viewing window in outer space. Very customizable with options
4) Bigscreen: A great and free* way to watch movies, including 3D (no glasses) movies and lots of TV channels. It sort of double's on virtual desktop's functionality but has "other people" who can screen their movies and watch with you. The * is that they have 4 movies weekly you can "buy" a ticket for $3.99. But there are constant user movies being screened for free if that doesn't appeal to you.
5) VRchat: Beginning to show its age but still the easiest way for casual socialization on VR.
6) I'll mention that there are a lot of short and cheap/free fully 3D Movies on Steam that are worth a view, such as "A Conscious Mind", music videos, etc.