Fang is pretty good but I don't find her versatile enough to be what I want. I use Sazh, Lightning, and Hope currently. If I find a fight is tough I switch out Hope for Vanille because her SAB stuff can be pretty delicious.

I start with SYN/MED/SYN so I can get Haste and Protect up, then I change to Diversity (COM/RAV/MED). I have Thaumaturgy (RAV/RAV/MED) and Tri-Disaster (RAVx3) in there as well. Can't remember the other two.