Best Keyblades (Birth by Sleep)

Terra: Chaos Ripper ATK: 10, MAG: -2, REACH: Long
Seeing as Terra has NO need for magic other than to fight Vanitas' Lingering Spirit, Strength is a huge priority, you can obtain this from defeating Master Eraqus in the Land of Departure.

Ventus: Ultima Weapon ATK: 7, MAG: 6, REACH: Long / No Name ATK: 6, MAG: 7, REACH: Long
Ventus really has no best weapon aside from these two, since he is so balanced and Ultima Weapon and No Name are both high in stats and balanced by themselves, he can choose either one. Ultima Weapon can be obtained by overcoming Villain's Vendetta in the Mirage Arena. No Name can be obtained by defeating Mysterious Figure.

Aqua: No Name ATK: 6, MAG: 7, REACH: Long
Since Aqua's best attacks are all spells, she needs as much of a boost in MAG as possible. Although you can also use Brightcrest, but the ATK is lower, so it's all on how you use Aqua. No Name can be obtained by defeating Mysterius Figure. Brightcrest is automatically given to you in Final Episode.

Void Gear is better than Chaos Ripper. Same range, far better magic, and still pretty high attack. Terra is a tank but its not like spells are void to him... MAGNEGA

Magnega is best used to gather enemies around you and then pummel them with attacks. Terra's use for magic is pretty much nonexistant, and even with Chaos Ripper, Curaga heals him almost all the way which is more than enough.