We choose the Zeiss VR ONE because it fits our demand to use it we a lot of smartphones. You’re not bound to one brand.
The quality of this device is very good. The use a tray slot so you can easily slide the tray (with your smartphone) in and don’t have to worry about the smartphone will fall out.
There’s also ventilation openings to ease airflow and prevent fogging of lenses.

Another thing we like very much is the open source cad model to draw your own tray. We made one for the Xiaomi Mi4C because it has a great pixels density. 5.0inch and 1920×1080 pixels is all you need to start. We know that there are other devices with more dpi but the compare to the price/quality, it’s a good buy.

You can print this tray from the Zeiss VR ONE website [download] or you can buy it 3d printed throught Shapeways [link to product].