[More Cowbell]

2 Fighters, Black Mage, White Mage
I also beat the game once with 3 Fighters and a White Mage....
some times you would go in an just rape anything and other times you barely scraped by.

Honestly, using 4 red mages was the best combination. It allowed you to do pretty much everything you wanted all game long. The only downside was that without a fighter, you had no one that could use the XCalber late in the game. As a completionist, that always bugged me.

I also beat it with 4 fighters. Doing that you could really beat the tar out of everything, but you had to carry around a ton of potions...