Astro Bot is undoubtedly my favourite VR game of all time. And it so happened to be the first one I played as well, as it was one of the games included in the Mega Pack bundle. The introduction to the VR world I received blew me away. There were some fun and challenging platforming sections, but half the time I was just looking around appreciating my surroundings. In my opinion, Astro Bot provides the best VR experience.
Other VR games I enjoyed playing were Moss, Blood & Truth, Robinson: The Journey, Tiny Trax, Job Simulator and Ghost Giant.