It's not that the languages themselves are hard, but rather that the concepts they represent are unfamiliar. That's in fact why metaphors are useful in the first place. Even if I did have a favorite, though, that wouldn't say anything about anybody else. That said, let me address the issue of appropriateness of metaphors. If your friend thinks that the Servant metaphor made her feel negative about computers, it would certainly be silly for her to use it, or to have to use it.
All metaphors are lies, after all.
A computer really isn't a person, or a servant, or a god, or a desktop, and so on. It's just that pretending it is can sometimes help us cope better. Like all lies, metaphors and other symbols have to be judged on their usefulness, not on their intrinsic worth. Among our group, we have different metaphors for computers. In the first part of the lecture I go into some of those questions briefly, and then pick them up in the conclusion.