Primer of best practices
Beyond creating great experiences, the number one goal in VR should be the comfort of the user. Specifically, not making the user feel ill from motion sickness.
Input
In our work, we have found the user interface of the Vive, Oculus, and PSVR to be the most reliable, easiest to train and best suited for fine-tuned gestures and manipulation.
The HoloLens natural input gestures can take a few minutes to learn and the voice recognition, while very reliable, even in noisy conditions, can be tricky due to the nuances of language and the wide ranges of synonyms that exist. Grab/Pinch/Hold/Grasp/Clutch/Seize/Take can all mean the same thing to different users as can Drop/Place/Release/Let Go/Place here. Keeping vocabulary to a minimum while building in as much redundancy as possible is the best design choice.
For Cardboard VR (though it can be used in all the other systems), the most common user interface is simply gaze select. The user puts the cross-hair on an icon and holds...