Commando: Omega-Preorder DLC/Chichu. Omega is slow but majorly Strong while Chichu is faster but a little weaker according to max Crystarium.
Ravager: Lightning- DLC. Lightning is very fast and has elemental blitz and Thundaga. Her power is very balanced.
Synergist: Yakshini. Yak gets the best Syn Spells that can overpower all of the other Synergist.
Sentinel: Silver Chocobo. Give him the right Infusions and his 9k HP makes him unkillable.
Saboteur: Black Chocobo. Black learns most of the Level 2 debuffs and has abilitys to extend it's duration.
Medic: Green Chocobo/Flanitor Green is melee proof and learns improved Cure II. Infuse it with Esunaga/Esuna and it's the best Medic. Flanitor is very good if Feral Howl thanks to Hyper Rescue otherwise Green wins hands down.