It's a subjective question. Especially inclusive on non factory colors. You may as well ask the question what is your favorite color.
Here is the best answer to your question.
according to PPG’s annual survey of global color popularity, white ranked first (22 percent) and silver was second (20 percent), followed by black (19 percent), gray (12 percent), red (9 percent), natural (8 percent), blue (7 percent), green (2 percent) and other colors (1 percent).
In North America, white ranks first (21 percent), followed by black (19 percent), silver and gray (16 percent each), red (10 percent), blue (8 percent), natural (7 percent) and green (3 percent).
In Europe, white is also most popular (23 percent), followed by black (21 percent), gray (17 percent), silver (13 percent), blue, natural and red (7 percent each), other colors (3 percent) and green (2 percent).
In the Asia Pacific region, silver and white tied for most popular (23 percent each), followed by black (19 percent), natural (10 percent), red (9 percent), gray (8 percent), blue (7 percent) and green (1 percent).
Source.
http://www.ppg.com/en/newsroom/news/Pag ... 1010A.aspx