My favorite superheroine is Wonder Woman -- the Wonder Woman of the William Marston/Harry G. Peter period, with its heady mix of mythology, feminism, and B&D. The character's fortunes declined precipitously following Marston's death in 1947, and I don't think she's ever completely recovered, though she still has her moments.

I did, however, have a thing for Susan Storm, way back in the 1960s, though I've never been able to decide whether it was a warm&fuzzy thing (as in, I wish she was my sister) or a warm&kootchy thing (as in, I wish she was my love slave).