Well, what I like in anime maidens is a girl who's supernatural. By this, I don't just mean she works with supernatural stuff (as in Sailor Moon and about fifty other animes featuring pretty girls firing off magical blasts) but that she is a supernatural creature herself. Case in point: Ceres the Tennyo from Ayashi No Ceres, seen here in the mirror next to her fully human host Aya.
While there's no exact translation for "tennyo" in our language, the tennyo in Japanese mythology are something like the fairies of ancient Irish mythology, i.e. full-sized powerful women who aren't quite deities themselves, but do serve as stand-ins for fate and divine decree, doling out rewards and punishments.
Apart from Ceres there, I haven't seen a lot of other distinctly supernatural women of this sort in my animes, but Ai from Video Girl Ai is also something like what I have in mind: a distinctly human girl who's nonetheless more than human as well.
What really pushes my buttons with this kind of girl is the mixture of intimacy and independence: she can bond with you in ways ordinary people can't, and yet she's not bound by all of the same physical restrictions you are. Her very occupation is both to keep and be kept by the guy; while a lot of these supernatural girls are obviously male fantasies personified, the ones in the better shows (such as these two) have minds of their own and can act on their own initiative. (In fact, in these two animes, they're often the ones running the show.)
I guess what I'm really saying is, if it comes down to what kind of anime girl I like, it's the kind who could haunt my house for me; it's not a paying occupation, but it would be very productive in its own way.