The characters with the best potential for

Strength - Steiner, Amarant, Zidane, Freya
Defence - Steiner, Freya
Magic + Magic Defence - Vivi, Eiko, Dagger, Quina

SO

Physical attack party - Zidane, Amarant, Freya, Steiner
Magical attack party - Zidane, Eiko, Vivi, Freya/Quina
All-round party - Zidane, Vivi, Freya, Amarant/Quina