i always try to give each character equal screen time in every FF.

One I liked using my first playthrough was Zidane, Amarant, Steiner, and Vivi.

the classic zidane, Steiner, Vivi and Garnet works fine.

With Freya, zidane, garnet, and eiko you can have one mage summoning, the other buffing and both healing, and good strength.