I'm going to post the main good and bad qualities of each Organization member just for kicks...
Axel
Good: Has the coolest attitude out of all the members/double agent.
Bad: Mainly concerned with looking out for #1...I mean #8, himself.
Larxene
Good: Hot.
Bad: Overly-fond of taunting/traitor.
Marluxia
Good: Main villain of Chain of Memories.
Bad: Uses flowers way too/traitor.
Vexen
Good: Smart.
Bad: Horribly annoying in battle.
Lexaeus
Good: Physically strongest of all the members.
Bad: A bully who wants to "bend Riku to his will".
Zexion
Good: Intelligent, calculative leader.
Bad: Lazy and not very powerful.