Oeilvert: Zidane, Dagger, Freya, Quina. I won't separate Zidane and Dagger, and Dagger is still having concentration issues, so she won't be too useful in the Desert Palace. Some playthroughs I switch Amarant and Quina.
Desert Palace: Eiko, Vivi, Steiner, Amarant. Eiko heals; Vivi can enable Steiner's magic swords. Amarant brings some offense and can restore MP with his Chakra ability.

Memoria: Zidane, Dagger, Freya, Amarant. Plenty of offense and Dagger keeps everyone healthy. Plus it keeps her with Zidane. Dagger has weapons with no back row penalty, so she can do some damage. It's those reasons I choose her over Eiko.