This question is not as subjective as it sounds.
Smartphones are commonly sold in black, white, silver, gold, and occasionally other colors. This is slightely dated (2013), but I'd like to assume the following typical usage pattern for a smartphone: People use smartphones in varied environments (home, office, transit, etc), so users may have all kinds of distractions, color and movement in the background while using the phone.
Question: what color smartphone provides the most immersive user experience?
For example, a black phone provides high contrast with the background, but the contrast boundary between the bezel and the content may be distracting. A white phone may provide too much glare. A silver phone may be neutral, but may cause screen content to bleed into the background. Gold may inject color-bias into the viewing experience.
I'm not familiar enough with visual design to know how to answer this question, so I'm looking for a answer that incorporates solid design principles and reasoning.
Please do not answer with personal color preferences because that is not what I'm looking for.