Welcome to Librarium Online!
I'm in the middle of painting a FW Avatar and have been posed a question by someone following my thread of the wip. "What craftworld is it from?" Now I haven't thought about that (I'm not an Eldar player) but wanted to know which craftworld would be the most prevelant so I could paint its tabard accordingly. The wip thread can be found in my sig'.
Help would be greatly appreciated on this.
Any craftworld would work but I agree that Biel tan is the fluffiest one. They used to take the avatar with a group of exarchs for an HQ. They have the court of the young king which is lead by an exarch until he is killed in awakening the avatar.