Mii Prototype Development History [From NES to Wii] GCD 2007

Currently Microsoft has issued a statement that their Avatars are based on WOW models, moreso than Nintendo's Miis. Of course this video completely predates the system based avatars all the way to Famicom.

Personally I like what they did with the 64 avatars. More detail and clothing options. I guess they were going for stylized looks rather than realism.