I started as a Warrior, Red Mage, Black Mage, Monk.
It didn't take too long to realize that the dedicated colour mages suck, so I switched the black to red for awhile.
Then I moved on to Knight, Red Mage, Dark Knight, Monk. I tried Geomancy and Scholar with the Dark Knight position, but they suck too.
My final config is Onion Knight, Sage, Dark Knight, Monk.
Ninjas are unfortunately ghey as they can only deal the max damage (which my Dark Knight already does PLUS self-heals with the Blood Sword) and they're limited in equipment - unlike the DK with her Masamune+Blood Sword comboÂ
The Monk can't be beat - I tried him as other things and he just kicks too much arse to be anything else. The Onion Knight is interesting, to say the least. Contrary to what some other douches have stated, the Onion is quite useful as early as you can get them....However, know that they are incredibly slow to gain stats. And once I started picking up the Onion items late in the game, he went from holding his own to straight holding it downÂ
p.s. : Keep swapping your Onion back and forth to Monk while leveling to maintain a decent HP gain rate.