It depends, I wear white in summers and black in winters to keep myself cool/hot
White does help prevent tanning really well. People ask me why I'm wearing a jacket in 90 degree weather and it's just because I don't want to burn
While black is USUALLY very slimming (believe it or not, I had a friend who could not wear black because it made her look very big, and she WASN'T- lol) but that is beside the point, it actually does NOT go with everything. White does however. Black really doesn't go with certain shades of brown or blue, such as Navy. I know that has gone "out the fashion window" so to speak, but it doesn't make it look any better.