I haven't played all the FFs I could have, but I think my party would be something like this.....

Cyan, so I can have a guy do cool things with sword
Shadow, because EVERY good party has a ninja
Ming-Wu, so I can heal people, and also to stop that silly trend of only using people from FF6
Krile as Summoner with Bl Magic, because 10 year old girls with nasty spells of devastation are awesome!

BTW, I'm just assuming we're using the classic 4 person set up, and not the 5 person setup of FF4 or the current 3 person party.