I don't remember Brenda (yeah, I only remember a "strange opening theme and the name of the show 90210 ) so I have to pick Prue...
She was my fav. character in charmed and I stopped watching the show when she died
. I'd like to say that as a first born she inspired me but... I'm the first born of twins XD (and my brother doesn't like when I act like the big sister, but he's way too imature !)