I know this probably differs by level, but what are your favorite six jobs to form a party? From about 30-50 this has been my ideal setup so far:

Paladin/Warrior (me! Taru PLDs are the best tanks ever)
White Mage/Black Mage (the lifeblood, and Regen and Haste are pretty nice)
Black Mage/White Mage (Does the most damage of any class)
Red Mage/White Mage (With Refresh and Convert there is never any downtime)
Dark Knight/Warrior (I've found them to be the most consistent DD melee, and they make good SATA partners)
Thief/Ninja (Man I love SATA, gives me a buttload of hate to start the battle and does some sweet damage, THF is a good puller too)

There are plenty of efficient parties but when I am forming a group and there are a lot of people looking I tend to fall back on this setup.