the color obviusly depends on ur choice, but if ure concerned about fading, Dont ever do for blue, Atleast the Toyota blue, it needs alot of maintainence looses its shine pretty soon, and fades easily.
Siliver is best color as stays as it is all round the year.
Gun mettalic is a gud color as well.
Brown? I think u meant the golden one (flacen mica) that color is also a cool color but to me looks gud in the altis (with side skirts rims and door strips etc)
White color, atleast i wont go for white, not being white is a edge to the Gli variant