i chose them because i wanted to have shading done with secondary colors (green, purple, orange), a yellow highlight (for the sun) and a red shadow (because hot shadows being an object forward)
other materials :
there is deviance within all materials, but in general:
metal, glass, water = high shine and reflection
leaves, polished stone, wet wood = some shine, little reflection
grass, rough stone, dry wood = little shine, little reflection