I'm not much of a magic user, but whether you love to just fight, or use magic, white magic is ey to surviving. Black magic is good to take out groups, but they can be dwindled with attacks as well. Blue magic is good, but depending on the game can be more of a pain to learn. White magic is just key to surviving. And when white magic includes spells like Aero/Holy it has those attack spells to help you out if needed.

SO yeah, white is the best because it is always useful.

THE JACKEL