My favorite classes would probably be:
Human: Thief w/ Blue Mage abilities & Double Sword
Moogle: Thief w/ Black Mage abilities & Counter
Bangaa: Defender w/ Monk Tech & Reflex
Viera: Assassin w/ White Mage abilities & Half MP
Nu mou: Sage w/ Alchemist abilities & Reflex *or* Beastmaster w/ Alchemist abilities and Reflex