I don't really have a preference, but I have noticed that the readings I have seen with white wall backgrounds have really been the worst. I am not sure why. Maybe its because by trying to make the artist's personal spaces into some neutral set, the focus goes to things that do not matter.
Laurie Metcalf's kitchen, Patti Lupone's air conditioner, Samira Wiley's gorgeous oversized wall tiles, and Allan Cumming's knicknacks may not have added anything, but they did not detract. The performers each seemed to be at home in their space and that translated to the performances.