I think Lady Russell was her intellectual equal in some ways, but Lady R was not musical as Lady Elliot, Anne and Frederick.

The Musgroves respected Anne, but there were not her intellectual equal -- chap 5 --
Mr. and Mrs. Musgrove were a very good sort of people; friendly and hospitable, not much educated, and not at all elegant. Their children had more modern minds and manners. There was a numerous family; but the only two grown up, excepting Charles, were Henrietta and Louisa ... Anne always contemplated them as some of the happiest creatures of her acquaintance: but still, saved as we all are by some comfortable feeling of superiority from wishing for the possibility of exchange, she would not have given up her own more elegant and cultivated mind for all their enjoyments; and envied them nothing but that seemingly perfect good understanding and agreement together, that good-humoured mutual affection, of which she had known so little herself with either of her sisters."