(I hope my post isn't too late, ah well.)
I'll list the party I used three times to beat the game.
(It's Refia, Luneth, Arc then Ingus)
First run:
Knight
Black Belt
Devout (Big mistake.)
Bard
XD Bard is probably the best class, which is why I refused to use one ever again. Devouts are so overrated. Their stats are inferior to the White Mage in many ways, and weaker spells casted by a job 99 White Mage are just as good as stronger spells casted by a job 99 Devout. Sure I have no Full Life, but no one needs it.
Second run:
Red Mage
Scholar
Viking
White Mage
Scholar is a very good support class, but they never see a good defensive score even from the back row. But it's nice practically being immune to magic, and the Viking remedies the physical problem... but they have horrible Magic Def so my Viking died a lot. =(
Third Run:
White Mage
Geomancer
Geomancer
Dragoon
This was the funnest and most effective party yet. No worries about physical or magic damage since I have a Hasted Dragoon with Gungir and Blood Lance in the air for boss battles. The only bad part of the game was that sunken temple since Whirlpool kept going off on the Geomancers. As late as the Eureka, boss battles would end after my Dragoon lands. Just in case I slip up with jumping, I wear Reflect Mail instead of Crystal Armor for boss battles so I don't get one-shotted by magic. (Superior Magic Def.)