HP: Basch --> Balthier
MP: Balthier --> Basch
Strength: Basch --> Balthier
Magicks Power: Basch --> Balthier
Vitality: Balthier --> Basch
Speed: Balthier --> Basch

Tie. I prefer Basch in terms of battle and stat. Basch+Axes+Shield=Unstoppable Killing Machine.
But Balthier surpasses Basch in terms of personality and character.