I like changing my avatar, too. In fact, I just changed from a messed up Alf avatar to a new Princess Mononoke one. I like that movie, and most other movies by that Myazaki fellow (the ones that I have seen were all great).
My favorite avatar I've ever had is either my first one, of GIR from invader Zim rding a pig, or What's-her-face from teen girl squad. But I like to keep it mixed.