Okay, I'm not asking for your "best" combination of materia, I'm only asking about crafty ones. Like this one:

Weapon: Hades=Added Effect, Destruct=Added Effect, Time=Added Effect, Poison=Elemental
Armor: Hades=Added Effect, Destruct=Added Effect, Time=Added Effect, Poison=Elemental
Accessory:Curse Ring

With this, you will possibly cause many different bad status to the target, including Slow and Stop. You will also protect yourself from them, and you will be able to attack yourself to heal. The Curse Ring is now ineffective, thanks to the Death protection, so you'll get a nice stats boost with no consequence (spelling?). I like to use this setup with Vincet...it just seems right, for some reason.

You could also create combos that benefit the whole party, like:

Character1
Weapon: Ice=Elemental
Armor: Lightning=Elemental

Character2
Weapon: Fire=Elemental
Armor: Ice=Elemental

Character3
Weapon: Lightning=Elemental
Armor: Fire=Elemental

With this, you could have the different character attack each other, in case the one you want to use for something else is in need of healing (like if s/he has a limit break).

Anybody else got something better (these are simple combos)?