White mage sucks you say? I finnished the game with 4x White Wizard at a level lower than my normal team (Master, Ninja, BW and WW)

Equip the masamune on the WW that has the highest strenght, use giants glove to spam saber on her, then use a hermes shoes. Caused 4000K damage with a physical attack on Chaos. That is, on the GBA and PSP version. The only boss that I found genuinely hard was Malirith. Took me 40 minutes to get rid of her.

A team of Black Wizard wasn't so bad either, at least up to where I got (Tiamat)

I'd probably say a team of master is the worst. Sure they are great... when they are supported by other classes, but alone? meh.